Issue MoonchildProductions/UXP#1578 - Add global menubar support for GTK

32 files changed, 4811 insertions, 4 deletions

diff --git a/layout/build/moz.build b/layout/build/moz.build
index b98e8265a..70b075491 100644
--- a/layout/build/moz.build
+++ b/layout/build/moz.build
@@ -73,6 +73,10 @@ elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'android':
         '/dom/system',
         '/dom/system/android',
     ]
+elif 'gtk' in CONFIG['MOZ_WIDGET_TOOLKIT']:
+    LOCAL_INCLUDES += [
+        '/widget/gtk',
+    ]
 
 if CONFIG['MOZ_WEBSPEECH']:
     LOCAL_INCLUDES += [
diff --git a/layout/build/nsLayoutStatics.cpp b/layout/build/nsLayoutStatics.cpp
index d71513268..6761931f6 100644
--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -124,6 +124,10 @@
 #include "mozilla/StaticPresData.h"
 #include "mozilla/dom/WebIDLGlobalNameHash.h"
 
+#ifdef MOZ_WIDGET_GTK
+#include "nsNativeMenuAtoms.h"
+#endif
+
 using namespace mozilla;
 using namespace mozilla::net;
 using namespace mozilla::dom;
@@ -158,6 +162,9 @@ nsLayoutStatics::Initialize()
   nsTextServicesDocument::RegisterAtoms();
   nsHTMLTags::RegisterAtoms();
   nsRDFAtoms::RegisterAtoms();
+#ifdef MOZ_WIDGET_GTK
+  nsNativeMenuAtoms::RegisterAtoms();
+#endif
 
   NS_SealStaticAtomTable();
 
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 17413b537..f3cf4c74e 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -251,6 +251,10 @@ pref("browser.sessionhistory.max_total_viewers", -1);
 pref("browser.newtabpage.add_to_session_history", false);
 
 pref("ui.use_native_colors", true);
+#ifdef MOZ_WIDGET_GTK
+// Determines whether the menubar is shown in the global menubar or not.
+pref("ui.use_global_menubar", false);
+#endif
 pref("ui.click_hold_context_menus", false);
 // Duration of timeout of incremental search in menus (ms).  0 means infinite.
 pref("ui.menu.incremental_search.timeout", 1000);
diff --git a/toolkit/content/widgets/popup.xml b/toolkit/content/widgets/popup.xml
index bb1a5eeee..43c529780 100644
--- a/toolkit/content/widgets/popup.xml
+++ b/toolkit/content/widgets/popup.xml
@@ -25,8 +25,14 @@
         </getter>
       </property>
 
-      <property name="state" readonly="true"
-                onget="return this.popupBoxObject.popupState"/>
+      <property name="state" readonly="true">
+        <getter><![CDATA[
+          if (this.hasAttribute('_moz-nativemenupopupstate'))
+            return this.getAttribute('_moz-nativemenupopupstate');
+          else
+            return this.popupBoxObject.popupState;
+        ]]></getter>
+      </property>
 
       <property name="triggerNode" readonly="true"
                 onget="return this.popupBoxObject.triggerNode"/>
diff --git a/toolkit/content/xul.css b/toolkit/content/xul.css
index 24a6713f9..0aa0d3a21 100644
--- a/toolkit/content/xul.css
+++ b/toolkit/content/xul.css
@@ -307,6 +307,15 @@ toolbar[type="menubar"][autohide="true"][inactive="true"]:not([customizing="true
 }
 %endif
 
+%ifdef MOZ_WIDGET_GTK
+window[shellshowingmenubar="true"] menubar,
+window[shellshowingmenubar="true"]
+toolbar[type="menubar"]:not([customizing="true"]) {
+  /* If a system-wide global menubar is in use, hide the XUL menubar. */
+  display: none !important;
+}
+%endif
+
 toolbarseparator {
   -moz-binding: url("chrome://global/content/bindings/toolbar.xml#toolbardecoration");
 }
diff --git a/widget/gtk/moz.build b/widget/gtk/moz.build
index baccb6ccd..8d621c0a0 100644
--- a/widget/gtk/moz.build
+++ b/widget/gtk/moz.build
@@ -24,10 +24,18 @@ UNIFIED_SOURCES += [
     'nsAppShell.cpp',
     'nsBidiKeyboard.cpp',
     'nsColorPicker.cpp',
+    'nsDbusmenu.cpp',
     'nsFilePicker.cpp',
     'nsGtkKeyUtils.cpp',
     'nsImageToPixbuf.cpp',
     'nsLookAndFeel.cpp',
+    'nsMenuBar.cpp',
+    'nsMenuContainer.cpp',
+    'nsMenuItem.cpp',
+    'nsMenuObject.cpp',
+    'nsMenuSeparator.cpp',
+    'nsNativeMenuAtoms.cpp',
+    'nsNativeMenuDocListener.cpp',
     'nsNativeThemeGTK.cpp',
     'nsScreenGtk.cpp',
     'nsScreenManagerGtk.cpp',
@@ -40,6 +48,8 @@ UNIFIED_SOURCES += [
 ]
 
 SOURCES += [
+    'nsMenu.cpp', # conflicts with X11 headers
+    'nsNativeMenuService.cpp',
     'nsWindow.cpp', # conflicts with X11 headers
 ]
 
@@ -104,6 +114,7 @@ FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
     '/layout/generic',
+    '/layout/style',
     '/layout/xul',
     '/other-licenses/atk-1.0',
     '/widget',
diff --git a/widget/gtk/nsDbusmenu.cpp b/widget/gtk/nsDbusmenu.cpp
new file mode 100644
index 000000000..2849536e9
--- /dev/null
+++ b/widget/gtk/nsDbusmenu.cpp
@@ -0,0 +1,59 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsDbusmenu.h"
+#include "prlink.h"
+#include "mozilla/ArrayUtils.h"
+
+#define FUNC(name, type, params) \
+nsDbusmenuFunctions::_##name##_fn nsDbusmenuFunctions::s_##name;
+DBUSMENU_GLIB_FUNCTIONS
+DBUSMENU_GTK_FUNCTIONS
+#undef FUNC
+
+static PRLibrary *gDbusmenuGlib = nullptr;
+static PRLibrary *gDbusmenuGtk = nullptr;
+
+typedef void (*nsDbusmenuFunc)();
+struct nsDbusmenuDynamicFunction {
+    const char *functionName;
+    nsDbusmenuFunc *function;
+};
+
+/* static */ nsresult
+nsDbusmenuFunctions::Init() {
+#define FUNC(name, type, params) \
+    { #name, (nsDbusmenuFunc *)&nsDbusmenuFunctions::s_##name },
+    static const nsDbusmenuDynamicFunction kDbusmenuGlibSymbols[] = {
+        DBUSMENU_GLIB_FUNCTIONS
+    };
+    static const nsDbusmenuDynamicFunction kDbusmenuGtkSymbols[] = {
+        DBUSMENU_GTK_FUNCTIONS
+    };
+
+#define LOAD_LIBRARY(symbol, name) \
+    if (!g##symbol) { \
+        g##symbol = PR_LoadLibrary(name); \
+        if (!g##symbol) { \
+            return NS_ERROR_FAILURE; \
+        } \
+    } \
+    for (uint32_t i = 0; i < mozilla::ArrayLength(k##symbol##Symbols); ++i) { \
+        *k##symbol##Symbols[i].function = \
+            PR_FindFunctionSymbol(g##symbol, k##symbol##Symbols[i].functionName); \
+        if (!*k##symbol##Symbols[i].function) { \
+            return NS_ERROR_FAILURE; \
+        } \
+    }
+
+    LOAD_LIBRARY(DbusmenuGlib, "libdbusmenu-glib.so.4")
+#if (MOZ_WIDGET_GTK == 3)
+    LOAD_LIBRARY(DbusmenuGtk, "libdbusmenu-gtk3.so.4")
+#else
+    LOAD_LIBRARY(DbusmenuGtk, "libdbusmenu-gtk.so.4")
+#endif
+#undef LOAD_LIBRARY
+
+    return NS_OK;
+}
diff --git a/widget/gtk/nsDbusmenu.h b/widget/gtk/nsDbusmenu.h
new file mode 100644
index 000000000..c0d9e7979
--- /dev/null
+++ b/widget/gtk/nsDbusmenu.h
@@ -0,0 +1,97 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsDbusmenu_h__
+#define __nsDbusmenu_h__
+
+#include "nsError.h"
+
+#include <glib.h>
+#include <gdk/gdk.h>
+
+#define DBUSMENU_GLIB_FUNCTIONS \
+    FUNC(dbusmenu_menuitem_child_add_position, gboolean, (DbusmenuMenuitem* mi, DbusmenuMenuitem* child, guint position)) \
+    FUNC(dbusmenu_menuitem_child_append, gboolean, (DbusmenuMenuitem* mi, DbusmenuMenuitem* child)) \
+    FUNC(dbusmenu_menuitem_child_delete, gboolean, (DbusmenuMenuitem* mi, DbusmenuMenuitem* child)) \
+    FUNC(dbusmenu_menuitem_get_children, GList*, (DbusmenuMenuitem* mi)) \
+    FUNC(dbusmenu_menuitem_new, DbusmenuMenuitem*, (void)) \
+    FUNC(dbusmenu_menuitem_property_get, const gchar*, (DbusmenuMenuitem* mi, const gchar* property)) \
+    FUNC(dbusmenu_menuitem_property_get_bool, gboolean, (DbusmenuMenuitem* mi, const gchar* property)) \
+    FUNC(dbusmenu_menuitem_property_remove, void, (DbusmenuMenuitem* mi, const gchar* property)) \
+    FUNC(dbusmenu_menuitem_property_set, gboolean, (DbusmenuMenuitem* mi, const gchar* property, const gchar* value)) \
+    FUNC(dbusmenu_menuitem_property_set_bool, gboolean, (DbusmenuMenuitem* mi, const gchar* property, const gboolean value)) \
+    FUNC(dbusmenu_menuitem_property_set_int, gboolean, (DbusmenuMenuitem* mi, const gchar* property, const gint value)) \
+    FUNC(dbusmenu_menuitem_show_to_user, void, (DbusmenuMenuitem* mi, guint timestamp)) \
+    FUNC(dbusmenu_menuitem_take_children, GList*, (DbusmenuMenuitem* mi)) \
+    FUNC(dbusmenu_server_new, DbusmenuServer*, (const gchar* object)) \
+    FUNC(dbusmenu_server_set_root, void, (DbusmenuServer* server, DbusmenuMenuitem* root)) \
+    FUNC(dbusmenu_server_set_status, void, (DbusmenuServer* server, DbusmenuStatus status))
+
+#define DBUSMENU_GTK_FUNCTIONS \
+    FUNC(dbusmenu_menuitem_property_set_image, gboolean, (DbusmenuMenuitem* menuitem, const gchar* property, const GdkPixbuf* data)) \
+    FUNC(dbusmenu_menuitem_property_set_shortcut, gboolean, (DbusmenuMenuitem* menuitem, guint key, GdkModifierType modifier))
+
+typedef struct _DbusmenuMenuitem DbusmenuMenuitem;
+typedef struct _DbusmenuServer DbusmenuServer;
+
+enum DbusmenuStatus {
+    DBUSMENU_STATUS_NORMAL,
+    DBUSMENU_STATUS_NOTICE
+};
+
+#define DBUSMENU_MENUITEM_CHILD_DISPLAY_SUBMENU "submenu"
+#define DBUSMENU_MENUITEM_PROP_CHILD_DISPLAY "children-display"
+#define DBUSMENU_MENUITEM_PROP_ENABLED "enabled"
+#define DBUSMENU_MENUITEM_PROP_ICON_DATA "icon-data"
+#define DBUSMENU_MENUITEM_PROP_LABEL "label"
+#define DBUSMENU_MENUITEM_PROP_SHORTCUT "shortcut"
+#define DBUSMENU_MENUITEM_PROP_TYPE "type"
+#define DBUSMENU_MENUITEM_PROP_TOGGLE_STATE "toggle-state"
+#define DBUSMENU_MENUITEM_PROP_TOGGLE_TYPE "toggle-type"
+#define DBUSMENU_MENUITEM_PROP_VISIBLE "visible"
+#define DBUSMENU_MENUITEM_SIGNAL_ABOUT_TO_SHOW "about-to-show"
+#define DBUSMENU_MENUITEM_SIGNAL_EVENT "event"
+#define DBUSMENU_MENUITEM_SIGNAL_ITEM_ACTIVATED "item-activated"
+#define DBUSMENU_MENUITEM_TOGGLE_CHECK "checkmark"
+#define DBUSMENU_MENUITEM_TOGGLE_RADIO "radio"
+#define DBUSMENU_MENUITEM_TOGGLE_STATE_CHECKED 1
+#define DBUSMENU_MENUITEM_TOGGLE_STATE_UNCHECKED 0
+#define DBUSMENU_SERVER_PROP_DBUS_OBJECT "dbus-object"
+
+class nsDbusmenuFunctions {
+public:
+    nsDbusmenuFunctions() = delete;
+
+    static nsresult Init();
+
+#define FUNC(name, type, params) \
+    typedef type (*_##name##_fn) params; \
+    static _##name##_fn s_##name;
+    DBUSMENU_GLIB_FUNCTIONS
+    DBUSMENU_GTK_FUNCTIONS
+#undef FUNC
+
+};
+
+#define dbusmenu_menuitem_child_add_position nsDbusmenuFunctions::s_dbusmenu_menuitem_child_add_position
+#define dbusmenu_menuitem_child_append nsDbusmenuFunctions::s_dbusmenu_menuitem_child_append
+#define dbusmenu_menuitem_child_delete nsDbusmenuFunctions::s_dbusmenu_menuitem_child_delete
+#define dbusmenu_menuitem_get_children nsDbusmenuFunctions::s_dbusmenu_menuitem_get_children
+#define dbusmenu_menuitem_new nsDbusmenuFunctions::s_dbusmenu_menuitem_new
+#define dbusmenu_menuitem_property_get nsDbusmenuFunctions::s_dbusmenu_menuitem_property_get
+#define dbusmenu_menuitem_property_get_bool nsDbusmenuFunctions::s_dbusmenu_menuitem_property_get_bool
+#define dbusmenu_menuitem_property_remove nsDbusmenuFunctions::s_dbusmenu_menuitem_property_remove
+#define dbusmenu_menuitem_property_set nsDbusmenuFunctions::s_dbusmenu_menuitem_property_set
+#define dbusmenu_menuitem_property_set_bool nsDbusmenuFunctions::s_dbusmenu_menuitem_property_set_bool
+#define dbusmenu_menuitem_property_set_int nsDbusmenuFunctions::s_dbusmenu_menuitem_property_set_int
+#define dbusmenu_menuitem_show_to_user nsDbusmenuFunctions::s_dbusmenu_menuitem_show_to_user
+#define dbusmenu_menuitem_take_children nsDbusmenuFunctions::s_dbusmenu_menuitem_take_children
+#define dbusmenu_server_new nsDbusmenuFunctions::s_dbusmenu_server_new
+#define dbusmenu_server_set_root nsDbusmenuFunctions::s_dbusmenu_server_set_root
+#define dbusmenu_server_set_status nsDbusmenuFunctions::s_dbusmenu_server_set_status
+
+#define dbusmenu_menuitem_property_set_image nsDbusmenuFunctions::s_dbusmenu_menuitem_property_set_image
+#define dbusmenu_menuitem_property_set_shortcut nsDbusmenuFunctions::s_dbusmenu_menuitem_property_set_shortcut
+
+#endif /* __nsDbusmenu_h__ */
diff --git a/widget/gtk/nsMenu.cpp b/widget/gtk/nsMenu.cpp
new file mode 100644
index 000000000..073a4acf6
--- /dev/null
+++ b/widget/gtk/nsMenu.cpp
@@ -0,0 +1,800 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#define _IMPL_NS_LAYOUT
+
+#include "mozilla/dom/Element.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/GuardObjects.h"
+#include "mozilla/MouseEvents.h"
+#include "mozilla/Move.h"
+#include "mozilla/StyleSetHandleInlines.h"
+#include "nsAutoPtr.h"
+#include "nsBindingManager.h"
+#include "nsComponentManagerUtils.h"
+#include "nsContentUtils.h"
+#include "nsCSSValue.h"
+#include "nsGkAtoms.h"
+#include "nsGtkUtils.h"
+#include "nsIAtom.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIPresShell.h"
+#include "nsIRunnable.h"
+#include "nsITimer.h"
+#include "nsString.h"
+#include "nsStyleContext.h"
+#include "nsStyleSet.h"
+#include "nsStyleStruct.h"
+#include "nsThreadUtils.h"
+#include "nsXBLBinding.h"
+#include "nsXBLService.h"
+
+#include "nsNativeMenuAtoms.h"
+#include "nsNativeMenuDocListener.h"
+
+#include <glib-object.h>
+
+#include "nsMenu.h"
+
+using namespace mozilla;
+
+class nsMenuContentInsertedEvent : public Runnable {
+public:
+    nsMenuContentInsertedEvent(nsMenu* aMenu,
+                               nsIContent* aContainer,
+                               nsIContent* aChild,
+                               nsIContent* aPrevSibling) :
+        mWeakMenu(aMenu),
+        mContainer(aContainer),
+        mChild(aChild),
+        mPrevSibling(aPrevSibling) { }
+
+    NS_IMETHODIMP Run() {
+        if (!mWeakMenu) {
+            return NS_OK;
+        }
+
+        static_cast<nsMenu *>(mWeakMenu.get())->HandleContentInserted(mContainer,
+                                                                      mChild,
+                                                                      mPrevSibling);
+        return NS_OK;
+    }
+
+private:
+    nsWeakMenuObject mWeakMenu;
+
+    nsCOMPtr<nsIContent> mContainer;
+    nsCOMPtr<nsIContent> mChild;
+    nsCOMPtr<nsIContent> mPrevSibling;
+};
+
+class nsMenuContentRemovedEvent : public Runnable {
+public:
+    nsMenuContentRemovedEvent(nsMenu* aMenu,
+                              nsIContent* aContainer,
+                              nsIContent* aChild) :
+        mWeakMenu(aMenu),
+        mContainer(aContainer),
+        mChild(aChild) { }
+
+    NS_IMETHODIMP Run() {
+        if (!mWeakMenu) {
+            return NS_OK;
+        }
+
+        static_cast<nsMenu *>(mWeakMenu.get())->HandleContentRemoved(mContainer,
+                                                                     mChild);
+        return NS_OK;
+    }
+
+private:
+    nsWeakMenuObject mWeakMenu;
+
+    nsCOMPtr<nsIContent> mContainer;
+    nsCOMPtr<nsIContent> mChild;
+};
+
+static void
+DispatchMouseEvent(nsIContent* aTarget, mozilla::EventMessage aMsg) {
+    if (!aTarget) {
+        return;
+    }
+
+    WidgetMouseEvent event(true, aMsg, nullptr, WidgetMouseEvent::eReal);
+    aTarget->DispatchDOMEvent(&event, nullptr, nullptr, nullptr);
+}
+
+static void
+AttachXBLBindings(nsIContent* aContent) {
+    nsIDocument* doc = aContent->OwnerDoc();
+    nsIPresShell* shell = doc->GetShell();
+    if (!shell) {
+        return;
+    }
+
+    RefPtr<nsStyleContext> sc =
+        shell->StyleSet()->AsGecko()->ResolveStyleFor(aContent->AsElement(),
+                                                      nullptr);
+    if (!sc) {
+        return;
+    }
+
+    const nsStyleDisplay* display = sc->StyleDisplay();
+    if (!display->mBinding) {
+        return;
+    }
+
+    nsXBLService* xbl = nsXBLService::GetInstance();
+    if (!xbl) {
+        return;
+    }
+
+    RefPtr<nsXBLBinding> binding;
+    bool dummy;
+    nsresult rv = xbl->LoadBindings(aContent, display->mBinding->GetURI(),
+                                    display->mBinding->mOriginPrincipal,
+                                    getter_AddRefs(binding), &dummy);
+    if ((NS_FAILED(rv) && rv != NS_ERROR_XBL_BLOCKED) || !binding) {
+        return;
+    }
+
+    doc->BindingManager()->AddToAttachedQueue(binding);
+}
+
+void
+nsMenu::SetPopupState(EPopupState aState) {
+    mPopupState = aState;
+
+    if (!mPopupContent) {
+        return;
+    }
+
+    nsAutoString state;
+    switch (aState) {
+        case ePopupState_Showing:
+            state.Assign(NS_LITERAL_STRING("showing"));
+            break;
+        case ePopupState_Open:
+            state.Assign(NS_LITERAL_STRING("open"));
+            break;
+        case ePopupState_Hiding:
+            state.Assign(NS_LITERAL_STRING("hiding"));
+            break;
+        default:
+            break;
+    }
+
+    if (state.IsEmpty()) {
+        mPopupContent->UnsetAttr(kNameSpaceID_None,
+                                 nsNativeMenuAtoms::_moz_nativemenupopupstate,
+                                 false);
+    } else {
+        mPopupContent->SetAttr(kNameSpaceID_None,
+                               nsNativeMenuAtoms::_moz_nativemenupopupstate,
+                               state, false);
+    }
+}
+
+/* static */ void
+nsMenu::DoOpenCallback(nsITimer* aTimer, void* aClosure) {
+    nsMenu* self = static_cast<nsMenu *>(aClosure);
+
+    dbusmenu_menuitem_show_to_user(self->GetNativeData(), 0);
+
+    self->mOpenDelayTimer = nullptr;
+}
+
+/* static */ void
+nsMenu::menu_event_cb(DbusmenuMenuitem* menu,
+                      const gchar* name,
+                      GVariant* value,
+                      guint timestamp,
+                      gpointer user_data) {
+    nsMenu* self = static_cast<nsMenu *>(user_data);
+
+    nsAutoCString event(name);
+
+    if (event.Equals(NS_LITERAL_CSTRING("closed"))) {
+        self->OnClose();
+        return;
+    }
+
+    if (event.Equals(NS_LITERAL_CSTRING("opened"))) {
+        self->OnOpen();
+        return;
+    }
+}
+
+void
+nsMenu::MaybeAddPlaceholderItem() {
+    MOZ_ASSERT(!IsInBatchedUpdate(),
+               "Shouldn't be modifying the native menu structure now");
+
+    GList* children = dbusmenu_menuitem_get_children(GetNativeData());
+    if (!children) {
+        MOZ_ASSERT(!mPlaceholderItem);
+
+        mPlaceholderItem = dbusmenu_menuitem_new();
+        if (!mPlaceholderItem) {
+            return;
+        }
+
+        dbusmenu_menuitem_property_set_bool(mPlaceholderItem,
+                                            DBUSMENU_MENUITEM_PROP_VISIBLE,
+                                            false);
+
+        MOZ_ALWAYS_TRUE(
+            dbusmenu_menuitem_child_append(GetNativeData(), mPlaceholderItem));
+    }
+}
+
+void
+nsMenu::EnsureNoPlaceholderItem() {
+    MOZ_ASSERT(!IsInBatchedUpdate(),
+               "Shouldn't be modifying the native menu structure now");
+
+    if (!mPlaceholderItem) {
+        return;
+    }
+
+    MOZ_ALWAYS_TRUE(
+        dbusmenu_menuitem_child_delete(GetNativeData(), mPlaceholderItem));
+    MOZ_ASSERT(!dbusmenu_menuitem_get_children(GetNativeData()));
+
+    g_object_unref(mPlaceholderItem);
+    mPlaceholderItem = nullptr;
+}
+
+void
+nsMenu::OnOpen() {
+    if (mNeedsRebuild) {
+        Build();
+    }
+
+    nsWeakMenuObject self(this);
+    nsCOMPtr<nsIContent> origPopupContent(mPopupContent);
+    {
+        nsNativeMenuDocListener::BlockUpdatesScope updatesBlocker;
+
+        SetPopupState(ePopupState_Showing);
+        DispatchMouseEvent(mPopupContent, eXULPopupShowing);
+
+        ContentNode()->SetAttr(kNameSpaceID_None, nsGkAtoms::open,
+                               NS_LITERAL_STRING("true"), true);
+    }
+
+    if (!self) {
+        // We were deleted!
+        return;
+    }
+
+    // I guess that the popup could have changed
+    if (origPopupContent != mPopupContent) {
+        return;
+    }
+
+    nsNativeMenuDocListener::BlockUpdatesScope updatesBlocker;
+
+    size_t count = ChildCount();
+    for (size_t i = 0; i < count; ++i) {
+        ChildAt(i)->ContainerIsOpening();
+    }
+
+    SetPopupState(ePopupState_Open);
+    DispatchMouseEvent(mPopupContent, eXULPopupShown);
+}
+
+void
+nsMenu::Build() {
+    mNeedsRebuild = false;
+
+    while (ChildCount() > 0) {
+        RemoveChildAt(0);
+    }
+
+    InitializePopup();
+
+    if (!mPopupContent) {
+        return;
+    }
+
+    uint32_t count = mPopupContent->GetChildCount();
+    for (uint32_t i = 0; i < count; ++i) {
+        nsIContent* childContent = mPopupContent->GetChildAt(i);
+
+        UniquePtr<nsMenuObject> child = CreateChild(childContent);
+
+        if (!child) {
+            continue;
+        }
+
+        AppendChild(Move(child));
+    }
+}
+
+void
+nsMenu::InitializePopup() {
+    nsCOMPtr<nsIContent> oldPopupContent;
+    oldPopupContent.swap(mPopupContent);
+
+    for (uint32_t i = 0; i < ContentNode()->GetChildCount(); ++i) {
+        nsIContent* child = ContentNode()->GetChildAt(i);
+
+        int32_t dummy;
+        nsCOMPtr<nsIAtom> tag = child->OwnerDoc()->BindingManager()->ResolveTag(child, &dummy);
+        if (tag == nsGkAtoms::menupopup) {
+            mPopupContent = child;
+            break;
+        }
+    }
+
+    if (oldPopupContent == mPopupContent) {
+        return;
+    }
+
+    // The popup has changed
+
+    if (oldPopupContent) {
+        DocListener()->UnregisterForContentChanges(oldPopupContent);
+    }
+
+    SetPopupState(ePopupState_Closed);
+
+    if (!mPopupContent) {
+        return;
+    }
+
+    AttachXBLBindings(mPopupContent);
+
+    DocListener()->RegisterForContentChanges(mPopupContent, this);
+}
+
+void
+nsMenu::RemoveChildAt(size_t aIndex) {
+    MOZ_ASSERT(IsInBatchedUpdate() || !mPlaceholderItem,
+               "Shouldn't have a placeholder menuitem");
+
+    nsMenuContainer::RemoveChildAt(aIndex, !IsInBatchedUpdate());
+    StructureMutated();
+
+    if (!IsInBatchedUpdate()) {
+        MaybeAddPlaceholderItem();
+    }
+}
+
+void
+nsMenu::RemoveChild(nsIContent* aChild) {
+    size_t index = IndexOf(aChild);
+    if (index == NoIndex) {
+        return;
+    }
+
+    RemoveChildAt(index);
+}
+
+void
+nsMenu::InsertChildAfter(UniquePtr<nsMenuObject> aChild,
+                         nsIContent* aPrevSibling) {
+    if (!IsInBatchedUpdate()) {
+        EnsureNoPlaceholderItem();
+    }
+
+    nsMenuContainer::InsertChildAfter(Move(aChild), aPrevSibling,
+                                      !IsInBatchedUpdate());
+    StructureMutated();
+}
+
+void
+nsMenu::AppendChild(UniquePtr<nsMenuObject> aChild) {
+    if (!IsInBatchedUpdate()) {
+        EnsureNoPlaceholderItem();
+    }
+
+    nsMenuContainer::AppendChild(Move(aChild), !IsInBatchedUpdate());
+    StructureMutated();
+}
+
+bool 
+nsMenu::IsInBatchedUpdate() const {
+    return mBatchedUpdateState != eBatchedUpdateState_Inactive;
+}
+
+void
+nsMenu::StructureMutated() {
+    if (!IsInBatchedUpdate()) {
+        return;
+    }
+
+    mBatchedUpdateState = eBatchedUpdateState_DidMutate;
+}
+
+bool
+nsMenu::CanOpen() const {
+    bool isVisible = dbusmenu_menuitem_property_get_bool(GetNativeData(),
+                                                         DBUSMENU_MENUITEM_PROP_VISIBLE);
+    bool isDisabled = ContentNode()->AttrValueIs(kNameSpaceID_None,
+                                                 nsGkAtoms::disabled,
+                                                 nsGkAtoms::_true,
+                                                 eCaseMatters);
+
+    return (isVisible && !isDisabled);
+}
+
+void
+nsMenu::HandleContentInserted(nsIContent* aContainer,
+                              nsIContent* aChild,
+                              nsIContent* aPrevSibling) {
+    if (aContainer == mPopupContent) {
+        UniquePtr<nsMenuObject> child = CreateChild(aChild);
+
+        if (child) {
+            InsertChildAfter(Move(child), aPrevSibling);
+        }
+    } else {
+        Build();
+    }
+}
+
+void
+nsMenu::HandleContentRemoved(nsIContent* aContainer, nsIContent* aChild) {
+    if (aContainer == mPopupContent) {
+        RemoveChild(aChild);
+    } else {
+        Build();
+    }
+}
+
+void
+nsMenu::InitializeNativeData() {
+    // Dbusmenu provides an "about-to-show" signal, and also "opened" and
+    // "closed" events. However, Unity is the only thing that sends
+    // both "about-to-show" and "opened" events. Unity 2D and the HUD only
+    // send "opened" events, so we ignore "about-to-show" (I don't think
+    // there's any real difference between them anyway).
+    // To complicate things, there are certain conditions where we don't
+    // get a "closed" event, so we need to be able to handle this :/
+    g_signal_connect(G_OBJECT(GetNativeData()), "event",
+                     G_CALLBACK(menu_event_cb), this);
+
+    mNeedsRebuild = true;
+    mNeedsUpdate = true;
+
+    MaybeAddPlaceholderItem();
+
+    AttachXBLBindings(ContentNode());
+}
+
+void
+nsMenu::Update(nsStyleContext* aStyleContext) {
+    if (mNeedsUpdate) {
+        mNeedsUpdate = false;
+
+        UpdateLabel();
+        UpdateSensitivity();
+    }
+
+    UpdateVisibility(aStyleContext);
+    UpdateIcon(aStyleContext);
+}
+
+nsMenuObject::PropertyFlags
+nsMenu::SupportedProperties() const {
+    return static_cast<nsMenuObject::PropertyFlags>(
+        nsMenuObject::ePropLabel |
+        nsMenuObject::ePropEnabled |
+        nsMenuObject::ePropVisible |
+        nsMenuObject::ePropIconData |
+        nsMenuObject::ePropChildDisplay
+    );
+}
+
+void
+nsMenu::OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) {
+    MOZ_ASSERT(aContent == ContentNode() || aContent == mPopupContent,
+               "Received an event that wasn't meant for us!");
+
+    if (mNeedsUpdate) {
+        return;
+    }
+
+    if (aContent != ContentNode()) {
+        return;
+    }
+
+    if (!Parent()->IsBeingDisplayed()) {
+        mNeedsUpdate = true;
+        return;
+    }
+
+    if (aAttribute == nsGkAtoms::disabled) {
+        UpdateSensitivity();
+    } else if (aAttribute == nsGkAtoms::label || 
+               aAttribute == nsGkAtoms::accesskey ||
+               aAttribute == nsGkAtoms::crop) {
+        UpdateLabel();
+    } else if (aAttribute == nsGkAtoms::hidden ||
+        aAttribute == nsGkAtoms::collapsed) {
+        RefPtr<nsStyleContext> sc = GetStyleContext();
+        UpdateVisibility(sc);
+    } else if (aAttribute == nsGkAtoms::image) {
+        RefPtr<nsStyleContext> sc = GetStyleContext();
+        UpdateIcon(sc);
+    }
+}
+
+void
+nsMenu::OnContentInserted(nsIContent* aContainer, nsIContent* aChild,
+                          nsIContent* aPrevSibling) {
+    MOZ_ASSERT(aContainer == ContentNode() || aContainer == mPopupContent,
+               "Received an event that wasn't meant for us!");
+
+    if (mNeedsRebuild) {
+        return;
+    }
+
+    if (mPopupState == ePopupState_Closed) {
+        mNeedsRebuild = true;
+        return;
+    }
+
+    nsContentUtils::AddScriptRunner(
+        new nsMenuContentInsertedEvent(this, aContainer, aChild,
+                                       aPrevSibling));
+}
+
+void
+nsMenu::OnContentRemoved(nsIContent* aContainer, nsIContent* aChild) {
+    MOZ_ASSERT(aContainer == ContentNode() || aContainer == mPopupContent,
+               "Received an event that wasn't meant for us!");
+
+    if (mNeedsRebuild) {
+        return;
+    }
+
+    if (mPopupState == ePopupState_Closed) {
+        mNeedsRebuild = true;
+        return;
+    }
+
+    nsContentUtils::AddScriptRunner(
+        new nsMenuContentRemovedEvent(this, aContainer, aChild));
+}
+
+/*
+ * Some menus (eg, the History menu in Firefox) refresh themselves on
+ * opening by removing all children and then re-adding new ones. As this
+ * happens whilst the menu is opening in Unity, it causes some flickering
+ * as the menu popup is resized multiple times. To avoid this, we try to
+ * reuse native menu items when the menu structure changes during a
+ * batched update. If we can handle menu structure changes from Goanna
+ * just by updating properties of native menu items (rather than destroying
+ * and creating new ones), then we eliminate any flickering that occurs as
+ * the menu is opened. To do this, we don't modify any native menu items
+ * until the end of the update batch.
+ */
+
+void
+nsMenu::OnBeginUpdates(nsIContent* aContent) {
+    MOZ_ASSERT(aContent == ContentNode() || aContent == mPopupContent,
+               "Received an event that wasn't meant for us!");
+    MOZ_ASSERT(!IsInBatchedUpdate(), "Already in an update batch!");
+
+    if (aContent != mPopupContent) {
+        return;
+    }
+
+    mBatchedUpdateState = eBatchedUpdateState_Active;
+}
+
+void
+nsMenu::OnEndUpdates() {
+    if (!IsInBatchedUpdate()) {
+        return;
+    }
+
+    bool didMutate = mBatchedUpdateState == eBatchedUpdateState_DidMutate;
+    mBatchedUpdateState = eBatchedUpdateState_Inactive;
+
+    /* Optimize for the case where we only had attribute changes */
+    if (!didMutate) {
+        return;
+    }
+
+    EnsureNoPlaceholderItem();
+
+    GList* nextNativeChild = dbusmenu_menuitem_get_children(GetNativeData());
+    DbusmenuMenuitem* nextOwnedNativeChild = nullptr;
+
+    size_t count = ChildCount();
+
+    // Find the first native menu item that is `owned` by a corresponding
+    // Goanna menuitem
+    for (size_t i = 0; i < count; ++i) {
+        if (ChildAt(i)->GetNativeData()) {
+            nextOwnedNativeChild = ChildAt(i)->GetNativeData();
+            break;
+        }
+    }
+
+    // Now iterate over all Goanna menuitems
+    for (size_t i = 0; i < count; ++i) {
+        nsMenuObject* child = ChildAt(i);
+
+        if (child->GetNativeData()) {
+            // This child already has a corresponding native menuitem.
+            // Remove all preceding orphaned native items. At this point, we
+            // modify the native menu structure.
+            while (nextNativeChild &&
+                   nextNativeChild->data != nextOwnedNativeChild) {
+
+                DbusmenuMenuitem* data =
+                    static_cast<DbusmenuMenuitem *>(nextNativeChild->data);
+                nextNativeChild = nextNativeChild->next;
+
+                MOZ_ALWAYS_TRUE(dbusmenu_menuitem_child_delete(GetNativeData(),
+                                                               data));
+            }
+
+            if (nextNativeChild) {
+                nextNativeChild = nextNativeChild->next;
+            }
+
+            // Now find the next native menu item that is `owned`
+            nextOwnedNativeChild = nullptr;
+            for (size_t j = i + 1; j < count; ++j) {
+                if (ChildAt(j)->GetNativeData()) {
+                    nextOwnedNativeChild = ChildAt(j)->GetNativeData();
+                    break;
+                }
+            }
+        } else {
+            // This child is new, and doesn't have a native menu item. Find one!
+            if (nextNativeChild &&
+                nextNativeChild->data != nextOwnedNativeChild) {
+
+                DbusmenuMenuitem* data =
+                    static_cast<DbusmenuMenuitem *>(nextNativeChild->data);
+
+                if (NS_SUCCEEDED(child->AdoptNativeData(data))) {
+                    nextNativeChild = nextNativeChild->next;
+                }
+            }
+
+            // There wasn't a suitable one available, so create a new one.
+            // At this point, we modify the native menu structure.
+            if (!child->GetNativeData()) {
+                child->CreateNativeData();
+                MOZ_ALWAYS_TRUE(
+                    dbusmenu_menuitem_child_add_position(GetNativeData(),
+                                                         child->GetNativeData(),
+                                                         i));
+            }
+        }
+    }
+
+    while (nextNativeChild) {
+        DbusmenuMenuitem* data =
+            static_cast<DbusmenuMenuitem *>(nextNativeChild->data);
+        nextNativeChild = nextNativeChild->next;
+
+        MOZ_ALWAYS_TRUE(dbusmenu_menuitem_child_delete(GetNativeData(), data));
+    }
+
+    MaybeAddPlaceholderItem();
+}
+
+nsMenu::nsMenu(nsMenuContainer* aParent, nsIContent* aContent) :
+    nsMenuContainer(aParent, aContent),
+    mNeedsRebuild(false),
+    mNeedsUpdate(false),
+    mPlaceholderItem(nullptr),
+    mPopupState(ePopupState_Closed),
+    mBatchedUpdateState(eBatchedUpdateState_Inactive) {
+    MOZ_COUNT_CTOR(nsMenu);
+}
+
+nsMenu::~nsMenu() {
+    if (IsInBatchedUpdate()) {
+        OnEndUpdates();
+    }
+
+    // Although nsTArray will take care of this in its destructor,
+    // we have to manually ensure children are removed from our native menu
+    // item, just in case our parent recycles us
+    while (ChildCount() > 0) {
+        RemoveChildAt(0);
+    }
+
+    EnsureNoPlaceholderItem();
+
+    if (DocListener() && mPopupContent) {
+        DocListener()->UnregisterForContentChanges(mPopupContent);
+    }
+
+    if (GetNativeData()) {
+        g_signal_handlers_disconnect_by_func(GetNativeData(),
+                                             FuncToGpointer(menu_event_cb),
+                                             this);
+    }
+
+    MOZ_COUNT_DTOR(nsMenu);
+}
+
+nsMenuObject::EType
+nsMenu::Type() const {
+    return eType_Menu;
+}
+
+bool
+nsMenu::IsBeingDisplayed() const {
+    return mPopupState == ePopupState_Open;
+}
+
+bool
+nsMenu::NeedsRebuild() const {
+    return mNeedsRebuild;
+}
+
+void
+nsMenu::OpenMenu() {
+    if (!CanOpen()) {
+        return;
+    }
+
+    if (mOpenDelayTimer) {
+        return;
+    }
+
+    // Here, we synchronously fire popupshowing and popupshown events and then
+    // open the menu after a short delay. This allows the menu to refresh before
+    // it's shown, and avoids an issue where keyboard focus is not on the first
+    // item of the history menu in Firefox when opening it with the keyboard,
+    // because extra items to appear at the top of the menu
+
+    OnOpen();
+
+    mOpenDelayTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
+    if (!mOpenDelayTimer) {
+        return;
+    }
+
+    if (NS_FAILED(mOpenDelayTimer->InitWithFuncCallback(DoOpenCallback,
+                                                        this,
+                                                        100,
+                                                        nsITimer::TYPE_ONE_SHOT))) {
+        mOpenDelayTimer = nullptr;
+    }
+}
+
+void
+nsMenu::OnClose() {
+    if (mPopupState == ePopupState_Closed) {
+        return;
+    }
+
+    MOZ_ASSERT(nsContentUtils::IsSafeToRunScript());
+
+    // We do this to avoid mutating our view of the menu until
+    // after we have finished
+    nsNativeMenuDocListener::BlockUpdatesScope updatesBlocker;
+
+    SetPopupState(ePopupState_Hiding);
+    DispatchMouseEvent(mPopupContent, eXULPopupHiding);
+
+    // Sigh, make sure all of our descendants are closed, as we don't
+    // always get closed events for submenus when scrubbing quickly through
+    // the menu
+    size_t count = ChildCount();
+    for (size_t i = 0; i < count; ++i) {
+        if (ChildAt(i)->Type() == nsMenuObject::eType_Menu) {
+            static_cast<nsMenu *>(ChildAt(i))->OnClose();
+        }
+    }
+
+    SetPopupState(ePopupState_Closed);
+    DispatchMouseEvent(mPopupContent, eXULPopupHidden);
+
+    ContentNode()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::open, true);
+}
diff --git a/widget/gtk/nsMenu.h b/widget/gtk/nsMenu.h
new file mode 100644
index 000000000..a198a8e72
--- /dev/null
+++ b/widget/gtk/nsMenu.h
@@ -0,0 +1,120 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenu_h__
+#define __nsMenu_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+#include "nsCOMPtr.h"
+
+#include "nsDbusmenu.h"
+#include "nsMenuContainer.h"
+#include "nsMenuObject.h"
+
+#include <glib.h>
+
+class nsIAtom;
+class nsIContent;
+class nsITimer;
+class nsStyleContext;
+
+#define NSMENU_NUMBER_OF_POPUPSTATE_BITS 2U
+#define NSMENU_NUMBER_OF_FLAGS           4U
+
+// This class represents a menu
+class nsMenu final : public nsMenuContainer {
+public:
+    nsMenu(nsMenuContainer* aParent, nsIContent* aContent);
+    ~nsMenu();
+
+    nsMenuObject::EType Type() const override;
+
+    bool IsBeingDisplayed() const override;
+    bool NeedsRebuild() const override;
+
+    // Tell the desktop shell to display this menu
+    void OpenMenu();
+
+    // Normally called via the shell, but it's public so that child
+    // menuitems can do the shells work. Sigh....
+    void OnClose();
+
+private:
+    friend class nsMenuContentInsertedEvent;
+    friend class nsMenuContentRemovedEvent;
+
+    enum EPopupState {
+        ePopupState_Closed,
+        ePopupState_Showing,
+        ePopupState_Open,
+        ePopupState_Hiding
+    };
+
+    void SetPopupState(EPopupState aState);
+
+    static void DoOpenCallback(nsITimer* aTimer, void* aClosure);
+    static void menu_event_cb(DbusmenuMenuitem* menu,
+                              const gchar* name,
+                              GVariant* value,
+                              guint timestamp,
+                              gpointer user_data);
+
+    // We add a placeholder item to empty menus so that Unity actually treats
+    // us as a proper menu, rather than a menuitem without a submenu
+    void MaybeAddPlaceholderItem();
+
+    // Removes a placeholder item if it exists and asserts that this succeeds
+    void EnsureNoPlaceholderItem();
+
+    void OnOpen();
+    void Build();
+    void InitializePopup();
+    void RemoveChildAt(size_t aIndex);
+    void RemoveChild(nsIContent* aChild);
+    void InsertChildAfter(mozilla::UniquePtr<nsMenuObject> aChild,
+                          nsIContent* aPrevSibling);
+    void AppendChild(mozilla::UniquePtr<nsMenuObject> aChild);
+    bool IsInBatchedUpdate() const;
+    void StructureMutated();
+    bool CanOpen() const;
+
+    void HandleContentInserted(nsIContent* aContainer,
+                               nsIContent* aChild,
+                               nsIContent* aPrevSibling);
+    void HandleContentRemoved(nsIContent* aContainer,
+                              nsIContent* aChild);
+
+    void InitializeNativeData() override;
+    void Update(nsStyleContext* aStyleContext) override;
+    nsMenuObject::PropertyFlags SupportedProperties() const override;
+
+    void OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) override;
+    void OnContentInserted(nsIContent* aContainer, nsIContent* aChild,
+                           nsIContent* aPrevSibling) override;
+    void OnContentRemoved(nsIContent* aContainer, nsIContent* aChild) override;
+    void OnBeginUpdates(nsIContent* aContent) override;
+    void OnEndUpdates() override;
+
+    bool mNeedsRebuild;
+    bool mNeedsUpdate;
+
+    DbusmenuMenuitem* mPlaceholderItem;
+
+    EPopupState mPopupState;
+
+    enum EBatchedUpdateState {
+        eBatchedUpdateState_Inactive,
+        eBatchedUpdateState_Active,
+        eBatchedUpdateState_DidMutate
+    };
+
+    EBatchedUpdateState mBatchedUpdateState;
+
+    nsCOMPtr<nsIContent> mPopupContent;
+
+    nsCOMPtr<nsITimer> mOpenDelayTimer;
+};
+
+#endif /* __nsMenu_h__ */
diff --git a/widget/gtk/nsMenuBar.cpp b/widget/gtk/nsMenuBar.cpp
new file mode 100644
index 000000000..e7caf119c
--- /dev/null
+++ b/widget/gtk/nsMenuBar.cpp
@@ -0,0 +1,541 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/Move.h"
+#include "mozilla/Preferences.h"
+#include "nsAutoPtr.h"
+#include "nsContentUtils.h"
+#include "nsIDocument.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMEventListener.h"
+#include "nsIDOMEventTarget.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIRunnable.h"
+#include "nsIWidget.h"
+#include "nsTArray.h"
+#include "nsUnicharUtils.h"
+
+#include "nsMenu.h"
+#include "nsNativeMenuAtoms.h"
+#include "nsNativeMenuService.h"
+
+#include <gdk/gdk.h>
+#include <gdk/gdkx.h>
+#include <glib.h>
+#include <glib-object.h>
+
+#include "nsMenuBar.h"
+
+using namespace mozilla;
+
+static bool
+ShouldHandleKeyEvent(nsIDOMEvent* aEvent) {
+    bool handled, trusted = false;
+    aEvent->GetPreventDefault(&handled);
+    aEvent->GetIsTrusted(&trusted);
+
+    if (handled || !trusted) {
+        return false;
+    }
+
+    return true;
+}
+
+class nsMenuBarContentInsertedEvent : public Runnable {
+public:
+    nsMenuBarContentInsertedEvent(nsMenuBar* aMenuBar,
+                                  nsIContent* aChild,
+                                  nsIContent* aPrevSibling) :
+        mWeakMenuBar(aMenuBar),
+        mChild(aChild),
+        mPrevSibling(aPrevSibling) { }
+
+    NS_IMETHODIMP Run()
+    {
+        if (!mWeakMenuBar) {
+            return NS_OK;
+        }
+
+        static_cast<nsMenuBar* >(mWeakMenuBar.get())->HandleContentInserted(mChild,
+                                                                            mPrevSibling);
+        return NS_OK;
+    }
+
+private:
+    nsWeakMenuObject mWeakMenuBar;
+
+    nsCOMPtr<nsIContent> mChild;
+    nsCOMPtr<nsIContent> mPrevSibling;
+};
+
+class nsMenuBarContentRemovedEvent : public Runnable {
+public:
+    nsMenuBarContentRemovedEvent(nsMenuBar* aMenuBar,
+                                 nsIContent* aChild) :
+        mWeakMenuBar(aMenuBar),
+        mChild(aChild) { }
+
+    NS_IMETHODIMP Run()
+    {
+        if (!mWeakMenuBar) {
+            return NS_OK;
+        }
+
+        static_cast<nsMenuBar* >(mWeakMenuBar.get())->HandleContentRemoved(mChild);
+        return NS_OK;
+    }
+
+private:
+    nsWeakMenuObject mWeakMenuBar;
+
+    nsCOMPtr<nsIContent> mChild;
+};
+
+class nsMenuBar::DocEventListener final : public nsIDOMEventListener {
+public:
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSIDOMEVENTLISTENER
+
+    DocEventListener(nsMenuBar* aOwner) : mOwner(aOwner) { };
+
+private:
+    ~DocEventListener() { };
+
+    nsMenuBar* mOwner;
+};
+
+NS_IMPL_ISUPPORTS(nsMenuBar::DocEventListener, nsIDOMEventListener)
+
+NS_IMETHODIMP
+nsMenuBar::DocEventListener::HandleEvent(nsIDOMEvent* aEvent) {
+    nsAutoString type;
+    nsresult rv = aEvent->GetType(type);
+    if (NS_FAILED(rv)) {
+        NS_WARNING("Failed to determine event type");
+        return rv;
+    }
+
+    if (type.Equals(NS_LITERAL_STRING("focus"))) {
+        mOwner->Focus();
+    } else if (type.Equals(NS_LITERAL_STRING("blur"))) {
+        mOwner->Blur();
+    } else if (type.Equals(NS_LITERAL_STRING("keypress"))) {
+        rv = mOwner->Keypress(aEvent);
+    } else if (type.Equals(NS_LITERAL_STRING("keydown"))) {
+        rv = mOwner->KeyDown(aEvent);
+    } else if (type.Equals(NS_LITERAL_STRING("keyup"))) {
+        rv = mOwner->KeyUp(aEvent);
+    }
+
+    return rv;
+}
+
+nsMenuBar::nsMenuBar(nsIContent* aMenuBarNode) :
+    nsMenuContainer(new nsNativeMenuDocListener(aMenuBarNode), aMenuBarNode),
+    mTopLevel(nullptr),
+    mServer(nullptr),
+    mIsActive(false) {
+    MOZ_COUNT_CTOR(nsMenuBar);
+}
+
+nsresult
+nsMenuBar::Init(nsIWidget* aParent) {
+    MOZ_ASSERT(aParent);
+
+    GdkWindow* gdkWin = static_cast<GdkWindow* >(
+        aParent->GetNativeData(NS_NATIVE_WINDOW));
+    if (!gdkWin) {
+        return NS_ERROR_FAILURE;
+    }
+
+    gpointer user_data = nullptr;
+    gdk_window_get_user_data(gdkWin, &user_data);
+    if (!user_data || !GTK_IS_CONTAINER(user_data)) {
+        return NS_ERROR_FAILURE;
+    }
+
+    mTopLevel = gtk_widget_get_toplevel(GTK_WIDGET(user_data));
+    if (!mTopLevel) {
+        return NS_ERROR_FAILURE;
+    }
+
+    g_object_ref(mTopLevel);
+
+    nsAutoCString path;
+    path.Append(NS_LITERAL_CSTRING("/com/canonical/menu/"));
+    char xid[10];
+    sprintf(xid, "%X", static_cast<uint32_t>(
+        GDK_WINDOW_XID(gtk_widget_get_window(mTopLevel))));
+    path.Append(xid);
+
+    mServer = dbusmenu_server_new(path.get());
+    if (!mServer) {
+        return NS_ERROR_FAILURE;
+    }
+
+    CreateNativeData();
+    if (!GetNativeData()) {
+        return NS_ERROR_FAILURE;
+    }
+
+    dbusmenu_server_set_root(mServer, GetNativeData());
+
+    mEventListener = new DocEventListener(this);
+
+    mDocument = do_QueryInterface(ContentNode()->OwnerDoc());
+
+    mAccessKey = Preferences::GetInt("ui.key.menuAccessKey");
+    if (mAccessKey == nsIDOMKeyEvent::DOM_VK_SHIFT) {
+        mAccessKeyMask = eModifierShift;
+    } else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_CONTROL) {
+        mAccessKeyMask = eModifierCtrl;
+    } else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_ALT) {
+        mAccessKeyMask = eModifierAlt;
+    } else if (mAccessKey == nsIDOMKeyEvent::DOM_VK_META) {
+        mAccessKeyMask = eModifierMeta;
+    } else {
+        mAccessKeyMask = eModifierAlt;
+    }
+
+    return NS_OK;
+}
+
+void
+nsMenuBar::Build() {
+    uint32_t count = ContentNode()->GetChildCount();
+    for (uint32_t i = 0; i < count; ++i) {
+        nsIContent* childContent = ContentNode()->GetChildAt(i);
+
+        UniquePtr<nsMenuObject> child = CreateChild(childContent);
+
+        if (!child) {
+            continue;
+        }
+
+        AppendChild(Move(child));
+    }
+}
+
+void
+nsMenuBar::DisconnectDocumentEventListeners() {
+    mDocument->RemoveEventListener(NS_LITERAL_STRING("focus"),
+                                   mEventListener,
+                                   true);
+    mDocument->RemoveEventListener(NS_LITERAL_STRING("blur"),
+                                   mEventListener,
+                                   true);
+    mDocument->RemoveEventListener(NS_LITERAL_STRING("keypress"),
+                                   mEventListener,
+                                   false);
+    mDocument->RemoveEventListener(NS_LITERAL_STRING("keydown"),
+                                   mEventListener,
+                                   false);
+    mDocument->RemoveEventListener(NS_LITERAL_STRING("keyup"),
+                                   mEventListener,
+                                   false);
+}
+
+void
+nsMenuBar::SetShellShowingMenuBar(bool aShowing) {
+    ContentNode()->OwnerDoc()->GetRootElement()->SetAttr(
+        kNameSpaceID_None, nsNativeMenuAtoms::shellshowingmenubar,
+        aShowing ? NS_LITERAL_STRING("true") : NS_LITERAL_STRING("false"),
+        true);
+}
+
+void
+nsMenuBar::Focus() {
+    ContentNode()->SetAttr(kNameSpaceID_None, nsNativeMenuAtoms::openedwithkey,
+                           NS_LITERAL_STRING("false"), true);
+}
+
+void
+nsMenuBar::Blur() {
+    // We do this here in case we lose focus before getting the
+    // keyup event, which leaves the menubar state looking like
+    // the alt key is stuck down
+    dbusmenu_server_set_status(mServer, DBUSMENU_STATUS_NORMAL);
+}
+
+nsMenuBar::ModifierFlags
+nsMenuBar::GetModifiersFromEvent(nsIDOMKeyEvent* aEvent) {
+    ModifierFlags modifiers = static_cast<ModifierFlags>(0);
+    bool modifier;
+
+    aEvent->GetAltKey(&modifier);
+    if (modifier) {
+        modifiers = static_cast<ModifierFlags>(modifiers | eModifierAlt);
+    }
+
+    aEvent->GetShiftKey(&modifier);
+    if (modifier) {
+        modifiers = static_cast<ModifierFlags>(modifiers | eModifierShift);
+    }
+
+    aEvent->GetCtrlKey(&modifier);
+    if (modifier) {
+        modifiers = static_cast<ModifierFlags>(modifiers | eModifierCtrl);
+    }
+
+    aEvent->GetMetaKey(&modifier);
+    if (modifier) {
+        modifiers = static_cast<ModifierFlags>(modifiers | eModifierMeta);
+    }
+
+    return modifiers;
+}
+
+nsresult
+nsMenuBar::Keypress(nsIDOMEvent* aEvent) {
+    if (!ShouldHandleKeyEvent(aEvent)) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aEvent);
+    if (!keyEvent) {
+        return NS_OK;
+    }
+
+    ModifierFlags modifiers = GetModifiersFromEvent(keyEvent);
+    if (((modifiers & mAccessKeyMask) == 0) ||
+        ((modifiers & ~mAccessKeyMask) != 0)) {
+        return NS_OK;
+    }
+
+    uint32_t charCode;
+    keyEvent->GetCharCode(&charCode);
+    if (charCode == 0) {
+        return NS_OK;
+    }
+
+    char16_t ch = char16_t(charCode);
+    char16_t chl = ToLowerCase(ch);
+    char16_t chu = ToUpperCase(ch);
+
+    nsMenuObject* found = nullptr;
+    uint32_t count = ChildCount();
+    for (uint32_t i = 0; i < count; ++i) {
+        nsAutoString accesskey;
+        ChildAt(i)->ContentNode()->GetAttr(kNameSpaceID_None,
+                                           nsGkAtoms::accesskey,
+                                           accesskey);
+        const nsAutoString::char_type* key = accesskey.BeginReading();
+        if (*key == chu ||* key == chl) {
+            found = ChildAt(i);
+            break;
+        }
+    }
+
+    if (!found || found->Type() != nsMenuObject::eType_Menu) {
+        return NS_OK;
+    }
+
+    ContentNode()->SetAttr(kNameSpaceID_None, nsNativeMenuAtoms::openedwithkey,
+                           NS_LITERAL_STRING("true"), true);
+    static_cast<nsMenu* >(found)->OpenMenu();
+
+    aEvent->StopPropagation();
+    aEvent->PreventDefault();
+
+    return NS_OK;
+}
+
+nsresult
+nsMenuBar::KeyDown(nsIDOMEvent* aEvent) {
+    if (!ShouldHandleKeyEvent(aEvent)) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aEvent);
+    if (!keyEvent) {
+        return NS_OK;
+    }
+
+    uint32_t keyCode;
+    keyEvent->GetKeyCode(&keyCode);
+    ModifierFlags modifiers = GetModifiersFromEvent(keyEvent);
+    if ((keyCode != mAccessKey) || ((modifiers & ~mAccessKeyMask) != 0)) {
+        return NS_OK;
+    }
+
+    dbusmenu_server_set_status(mServer, DBUSMENU_STATUS_NOTICE);
+
+    return NS_OK;
+}
+
+nsresult
+nsMenuBar::KeyUp(nsIDOMEvent* aEvent) {
+    if (!ShouldHandleKeyEvent(aEvent)) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent = do_QueryInterface(aEvent);
+    if (!keyEvent) {
+        return NS_OK;
+    }
+
+    uint32_t keyCode;
+    keyEvent->GetKeyCode(&keyCode);
+    if (keyCode == mAccessKey) {
+        dbusmenu_server_set_status(mServer, DBUSMENU_STATUS_NORMAL);
+    }
+
+    return NS_OK;
+}
+
+void
+nsMenuBar::HandleContentInserted(nsIContent* aChild, nsIContent* aPrevSibling) {
+    UniquePtr<nsMenuObject> child = CreateChild(aChild);
+
+    if (!child) {
+        return;
+    }
+
+    InsertChildAfter(Move(child), aPrevSibling);
+}
+
+void
+nsMenuBar::HandleContentRemoved(nsIContent* aChild) {
+    RemoveChild(aChild);
+}
+
+void
+nsMenuBar::OnContentInserted(nsIContent* aContainer, nsIContent* aChild,
+                             nsIContent* aPrevSibling) {
+    MOZ_ASSERT(aContainer == ContentNode(),
+               "Received an event that wasn't meant for us");
+
+    nsContentUtils::AddScriptRunner(
+        new nsMenuBarContentInsertedEvent(this, aChild, aPrevSibling));
+}
+
+void
+nsMenuBar::OnContentRemoved(nsIContent* aContainer, nsIContent* aChild) {
+    MOZ_ASSERT(aContainer == ContentNode(),
+               "Received an event that wasn't meant for us");
+
+    nsContentUtils::AddScriptRunner(
+        new nsMenuBarContentRemovedEvent(this, aChild));
+}
+
+nsMenuBar::~nsMenuBar() {
+    nsNativeMenuService* service = nsNativeMenuService::GetSingleton();
+    if (service) {
+        service->NotifyNativeMenuBarDestroyed(this);
+    }
+
+    if (ContentNode()) {
+        SetShellShowingMenuBar(false);
+    }
+
+    // We want to destroy all children before dropping our reference
+    // to the doc listener
+    while (ChildCount() > 0) {
+        RemoveChildAt(0);
+    }
+
+    if (mTopLevel) {
+        g_object_unref(mTopLevel);
+    }
+
+    if (DocListener()) {
+        DocListener()->Stop();
+    }
+
+    if (mDocument) {
+        DisconnectDocumentEventListeners();
+    }
+
+    if (mServer) {
+        g_object_unref(mServer);
+    }
+
+    MOZ_COUNT_DTOR(nsMenuBar);
+}
+
+/* static */ UniquePtr<nsMenuBar>
+nsMenuBar::Create(nsIWidget* aParent, nsIContent* aMenuBarNode) {
+    UniquePtr<nsMenuBar> menubar(new nsMenuBar(aMenuBarNode));
+    if (NS_FAILED(menubar->Init(aParent))) {
+        return nullptr;
+    }
+
+    return Move(menubar);
+}
+
+nsMenuObject::EType
+nsMenuBar::Type() const {
+    return eType_MenuBar;
+}
+
+bool
+nsMenuBar::IsBeingDisplayed() const {
+    return true;
+}
+
+uint32_t
+nsMenuBar::WindowId() const {
+    return static_cast<uint32_t>(GDK_WINDOW_XID(gtk_widget_get_window(mTopLevel)));
+}
+
+nsAdoptingCString
+nsMenuBar::ObjectPath() const {
+    gchar* tmp;
+    g_object_get(mServer, DBUSMENU_SERVER_PROP_DBUS_OBJECT, &tmp, NULL);
+    nsAdoptingCString result(tmp);
+
+    return result;
+}
+
+void
+nsMenuBar::Activate() {
+    if (mIsActive) {
+        return;
+    }
+
+    mIsActive = true;
+
+    mDocument->AddEventListener(NS_LITERAL_STRING("focus"),
+                                mEventListener,
+                                true);
+    mDocument->AddEventListener(NS_LITERAL_STRING("blur"),
+                                mEventListener,
+                                true);
+    mDocument->AddEventListener(NS_LITERAL_STRING("keypress"),
+                                mEventListener,
+                                false);
+    mDocument->AddEventListener(NS_LITERAL_STRING("keydown"),
+                                mEventListener,
+                                false);
+    mDocument->AddEventListener(NS_LITERAL_STRING("keyup"),
+                                mEventListener,
+                                false);
+
+    // Clear this. Not sure if we really need to though
+    ContentNode()->SetAttr(kNameSpaceID_None, nsNativeMenuAtoms::openedwithkey,
+                           NS_LITERAL_STRING("false"), true);
+
+    DocListener()->Start();
+    Build();
+    SetShellShowingMenuBar(true);
+}
+
+void
+nsMenuBar::Deactivate() {
+    if (!mIsActive) {
+        return;
+    }
+
+    mIsActive = false;
+
+    SetShellShowingMenuBar(false);
+    while (ChildCount() > 0) {
+        RemoveChildAt(0);
+    }
+    DocListener()->Stop();
+    DisconnectDocumentEventListeners();
+}
diff --git a/widget/gtk/nsMenuBar.h b/widget/gtk/nsMenuBar.h
new file mode 100644
index 000000000..9ce179651
--- /dev/null
+++ b/widget/gtk/nsMenuBar.h
@@ -0,0 +1,103 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenuBar_h__
+#define __nsMenuBar_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/UniquePtr.h"
+#include "nsCOMPtr.h"
+#include "nsString.h"
+
+#include "nsDbusmenu.h"
+#include "nsMenuContainer.h"
+#include "nsMenuObject.h"
+
+#include <gtk/gtk.h>
+
+class nsIAtom;
+class nsIContent;
+class nsIDOMEvent;
+class nsIDOMKeyEvent;
+class nsIWidget;
+class nsMenuBarDocEventListener;
+
+/*
+ * The menubar class. There is one of these per window (and the window
+ * owns its menubar). Each menubar has an object path, and the service is
+ * responsible for telling the desktop shell which object path corresponds
+ * to a particular window. A menubar and its hierarchy also own a
+ * nsNativeMenuDocListener.
+ */
+class nsMenuBar final : public nsMenuContainer {
+public:
+    ~nsMenuBar() override;
+
+    static mozilla::UniquePtr<nsMenuBar> Create(nsIWidget* aParent,
+                                                nsIContent* aMenuBarNode);
+
+    nsMenuObject::EType Type() const override;
+
+    bool IsBeingDisplayed() const override;
+
+    // Get the native window ID for this menubar
+    uint32_t WindowId() const;
+
+    // Get the object path for this menubar
+    nsAdoptingCString ObjectPath() const;
+
+    // Get the top-level GtkWindow handle
+    GtkWidget* TopLevelWindow() { return mTopLevel; }
+
+    // Called from the menuservice when the menubar is about to be registered.
+    // Causes the native menubar to be created, and the XUL menubar to be hidden
+    void Activate();
+
+    // Called from the menuservice when the menubar is no longer registered
+    // with the desktop shell. Will cause the XUL menubar to be shown again
+    void Deactivate();
+
+private:
+    class DocEventListener;
+    friend class nsMenuBarContentInsertedEvent;
+    friend class nsMenuBarContentRemovedEvent;
+
+    enum ModifierFlags {
+        eModifierShift = (1 << 0),
+        eModifierCtrl = (1 << 1),
+        eModifierAlt = (1 << 2),
+        eModifierMeta = (1 << 3)
+    };
+
+    nsMenuBar(nsIContent* aMenuBarNode);
+    nsresult Init(nsIWidget* aParent);
+    void Build();
+    void DisconnectDocumentEventListeners();
+    void SetShellShowingMenuBar(bool aShowing);
+    void Focus();
+    void Blur();
+    ModifierFlags GetModifiersFromEvent(nsIDOMKeyEvent* aEvent);
+    nsresult Keypress(nsIDOMEvent* aEvent);
+    nsresult KeyDown(nsIDOMEvent* aEvent);
+    nsresult KeyUp(nsIDOMEvent* aEvent);
+
+    void HandleContentInserted(nsIContent* aChild,
+                               nsIContent* aPrevSibling);
+    void HandleContentRemoved(nsIContent* aChild);
+
+    void OnContentInserted(nsIContent* aContainer, nsIContent* aChild,
+                           nsIContent* aPrevSibling) override;
+    void OnContentRemoved(nsIContent* aContainer, nsIContent* aChild) override;
+
+    GtkWidget* mTopLevel;
+    DbusmenuServer* mServer;
+    nsCOMPtr<nsIDOMEventTarget> mDocument;
+    RefPtr<DocEventListener> mEventListener;
+
+    uint32_t mAccessKey;
+    ModifierFlags mAccessKeyMask;
+    bool mIsActive;
+};
+
+#endif /* __nsMenuBar_h__ */
diff --git a/widget/gtk/nsMenuContainer.cpp b/widget/gtk/nsMenuContainer.cpp
new file mode 100644
index 000000000..081e98a6a
--- /dev/null
+++ b/widget/gtk/nsMenuContainer.cpp
@@ -0,0 +1,156 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ *  License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Move.h"
+#include "nsGkAtoms.h"
+#include "nsIAtom.h"
+#include "nsIContent.h"
+
+#include "nsDbusmenu.h"
+#include "nsMenu.h"
+#include "nsMenuItem.h"
+#include "nsMenuSeparator.h"
+
+#include "nsMenuContainer.h"
+
+using namespace mozilla;
+
+const nsMenuContainer::ChildTArray::index_type nsMenuContainer::NoIndex = nsMenuContainer::ChildTArray::NoIndex;
+
+typedef UniquePtr<nsMenuObject> (*nsMenuObjectConstructor)(nsMenuContainer*,
+                                                           nsIContent*);
+
+template<class T>
+static UniquePtr<nsMenuObject> CreateMenuObject(nsMenuContainer* aContainer,
+                                                nsIContent* aContent) {
+    return UniquePtr<T>(new T(aContainer, aContent));
+}
+
+static nsMenuObjectConstructor
+GetMenuObjectConstructor(nsIContent* aContent) {
+    if (aContent->IsXULElement(nsGkAtoms::menuitem)) {
+        return CreateMenuObject<nsMenuItem>;
+    } else if (aContent->IsXULElement(nsGkAtoms::menu)) {
+        return CreateMenuObject<nsMenu>;
+    } else if (aContent->IsXULElement(nsGkAtoms::menuseparator)) {
+        return CreateMenuObject<nsMenuSeparator>;
+    }
+
+    return nullptr;
+}
+
+static bool
+ContentIsSupported(nsIContent* aContent) {
+    return GetMenuObjectConstructor(aContent) ? true : false;
+}
+
+nsMenuContainer::nsMenuContainer(nsMenuContainer* aParent,
+                                 nsIContent* aContent) :
+    nsMenuObject(aParent, aContent) {
+}
+
+nsMenuContainer::nsMenuContainer(nsNativeMenuDocListener* aListener,
+                                 nsIContent* aContent) :
+    nsMenuObject(aListener, aContent) {
+}
+
+UniquePtr<nsMenuObject>
+nsMenuContainer::CreateChild(nsIContent* aContent) {
+    nsMenuObjectConstructor ctor = GetMenuObjectConstructor(aContent);
+    if (!ctor) {
+        // There are plenty of node types we might stumble across that
+        // aren't supported
+        return nullptr;
+    }
+
+    UniquePtr<nsMenuObject> res = ctor(this, aContent);
+    return Move(res);
+}
+
+size_t
+nsMenuContainer::IndexOf(nsIContent* aChild) const {
+    if (!aChild) {
+        return NoIndex;
+    }
+
+    size_t count = ChildCount();
+    for (size_t i = 0; i < count; ++i) {
+        if (ChildAt(i)->ContentNode() == aChild) {
+            return i;
+        }
+    }
+
+    return NoIndex;
+}
+
+void
+nsMenuContainer::RemoveChildAt(size_t aIndex, bool aUpdateNative) {
+    MOZ_ASSERT(aIndex < ChildCount());
+
+    if (aUpdateNative) {
+        MOZ_ALWAYS_TRUE(
+            dbusmenu_menuitem_child_delete(GetNativeData(),
+                                           ChildAt(aIndex)->GetNativeData()));
+    }
+
+    mChildren.RemoveElementAt(aIndex);
+}
+
+void
+nsMenuContainer::RemoveChild(nsIContent* aChild, bool aUpdateNative) {
+    size_t index = IndexOf(aChild);
+    if (index == NoIndex) {
+        return;
+    }
+
+    RemoveChildAt(index, aUpdateNative);
+}
+
+void
+nsMenuContainer::InsertChildAfter(UniquePtr<nsMenuObject> aChild,
+                                  nsIContent* aPrevSibling,
+                                  bool aUpdateNative) {
+    size_t index = IndexOf(aPrevSibling);
+    MOZ_ASSERT(!aPrevSibling || index != NoIndex);
+
+    ++index;
+
+    if (aUpdateNative) {
+        aChild->CreateNativeData();
+        MOZ_ALWAYS_TRUE(
+            dbusmenu_menuitem_child_add_position(GetNativeData(),
+                                                 aChild->GetNativeData(),
+                                                 index));
+    }
+
+    MOZ_ALWAYS_TRUE(mChildren.InsertElementAt(index, Move(aChild)));
+}
+
+void
+nsMenuContainer::AppendChild(UniquePtr<nsMenuObject> aChild,
+                             bool aUpdateNative) {
+    if (aUpdateNative) {
+        aChild->CreateNativeData();
+        MOZ_ALWAYS_TRUE(
+            dbusmenu_menuitem_child_append(GetNativeData(),
+                                           aChild->GetNativeData()));
+    }
+
+    MOZ_ALWAYS_TRUE(mChildren.AppendElement(Move(aChild)));
+}
+
+bool
+nsMenuContainer::NeedsRebuild() const {
+    return false;
+}
+
+/* static */ nsIContent*
+nsMenuContainer::GetPreviousSupportedSibling(nsIContent* aContent) {
+    do {
+        aContent = aContent->GetPreviousSibling();
+    } while (aContent && !ContentIsSupported(aContent));
+
+    return aContent;
+}
diff --git a/widget/gtk/nsMenuContainer.h b/widget/gtk/nsMenuContainer.h
new file mode 100644
index 000000000..95d65a2f1
--- /dev/null
+++ b/widget/gtk/nsMenuContainer.h
@@ -0,0 +1,66 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ *  License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenuContainer_h__
+#define __nsMenuContainer_h__
+
+#include "mozilla/UniquePtr.h"
+#include "nsTArray.h"
+
+#include "nsMenuObject.h"
+
+class nsIContent;
+class nsNativeMenuDocListener;
+
+// Base class for containers (menus and menubars)
+class nsMenuContainer : public nsMenuObject {
+public:
+    typedef nsTArray<mozilla::UniquePtr<nsMenuObject> > ChildTArray;
+
+    // Determine if this container is being displayed on screen. Must be
+    // implemented by subclasses. Must return true if the container is
+    // in the fully open state, or false otherwise
+    virtual bool IsBeingDisplayed() const = 0;
+
+    // Determine if this container will be rebuilt the next time it opens.
+    // Returns false by default but can be overridden by subclasses
+    virtual bool NeedsRebuild() const;
+
+    // Return the first previous sibling that is of a type supported by the
+    // menu system
+    static nsIContent* GetPreviousSupportedSibling(nsIContent* aContent);
+
+    static const ChildTArray::index_type NoIndex;
+
+protected:
+    nsMenuContainer(nsMenuContainer* aParent, nsIContent* aContent);
+    nsMenuContainer(nsNativeMenuDocListener* aListener, nsIContent* aContent);
+
+    // Create a new child element for the specified content node
+    mozilla::UniquePtr<nsMenuObject> CreateChild(nsIContent* aContent);
+
+    // Return the index of the child for the specified content node
+    size_t IndexOf(nsIContent* aChild) const;
+
+    size_t ChildCount() const { return mChildren.Length(); }
+    nsMenuObject* ChildAt(size_t aIndex) const { return mChildren[aIndex].get(); }
+
+    void RemoveChildAt(size_t aIndex, bool aUpdateNative = true);
+
+    // Remove the child that owns the specified content node
+    void RemoveChild(nsIContent* aChild, bool aUpdateNative = true);
+
+    // Insert a new child after the child that owns the specified content node
+    void InsertChildAfter(mozilla::UniquePtr<nsMenuObject> aChild,
+                          nsIContent* aPrevSibling,
+                          bool aUpdateNative = true);
+
+    void AppendChild(mozilla::UniquePtr<nsMenuObject> aChild,
+                     bool aUpdateNative = true);
+
+private:
+    ChildTArray mChildren;
+};
+
+#endif /* __nsMenuContainer_h__ */
diff --git a/widget/gtk/nsMenuItem.cpp b/widget/gtk/nsMenuItem.cpp
new file mode 100644
index 000000000..00cc5477c
--- /dev/null
+++ b/widget/gtk/nsMenuItem.cpp
@@ -0,0 +1,712 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/Move.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/TextEvents.h"
+#include "nsAutoPtr.h"
+#include "nsContentUtils.h"
+#include "nsCRT.h"
+#include "nsGkAtoms.h"
+#include "nsGtkUtils.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+#include "nsIDOMDocument.h"
+#include "nsIDOMEvent.h"
+#include "nsIDOMEventTarget.h"
+#include "nsIDOMKeyEvent.h"
+#include "nsIDOMXULCommandEvent.h"
+#include "nsIRunnable.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+#include "nsStyleContext.h"
+#include "nsThreadUtils.h"
+
+#include "nsMenu.h"
+#include "nsMenuBar.h"
+#include "nsMenuContainer.h"
+#include "nsNativeMenuDocListener.h"
+
+#include <gdk/gdk.h>
+#include <gdk/gdkkeysyms.h>
+#if (MOZ_WIDGET_GTK == 3)
+#include <gdk/gdkkeysyms-compat.h>
+#endif
+#include <gdk/gdkx.h>
+#include <gtk/gtk.h>
+
+#include "nsMenuItem.h"
+
+using namespace mozilla;
+
+struct KeyCodeData {
+    const char* str;
+    size_t strlength;
+    uint32_t keycode;
+};
+
+static struct KeyCodeData gKeyCodes[] = {
+#define NS_DEFINE_VK(aDOMKeyName, aDOMKeyCode) \
+  { #aDOMKeyName, sizeof(#aDOMKeyName) - 1, aDOMKeyCode },
+#include "mozilla/VirtualKeyCodeList.h"
+#undef NS_DEFINE_VK
+  { nullptr, 0, 0 }
+};
+
+struct KeyPair {
+    uint32_t DOMKeyCode;
+    guint GDKKeyval;
+};
+
+//
+// Netscape keycodes are defined in widget/public/nsGUIEvent.h
+// GTK keycodes are defined in <gdk/gdkkeysyms.h>
+//
+static const KeyPair gKeyPairs[] = {
+    { NS_VK_CANCEL,     GDK_Cancel },
+    { NS_VK_BACK,       GDK_BackSpace },
+    { NS_VK_TAB,        GDK_Tab },
+    { NS_VK_TAB,        GDK_ISO_Left_Tab },
+    { NS_VK_CLEAR,      GDK_Clear },
+    { NS_VK_RETURN,     GDK_Return },
+    { NS_VK_SHIFT,      GDK_Shift_L },
+    { NS_VK_SHIFT,      GDK_Shift_R },
+    { NS_VK_SHIFT,      GDK_Shift_Lock },
+    { NS_VK_CONTROL,    GDK_Control_L },
+    { NS_VK_CONTROL,    GDK_Control_R },
+    { NS_VK_ALT,        GDK_Alt_L },
+    { NS_VK_ALT,        GDK_Alt_R },
+    { NS_VK_META,       GDK_Meta_L },
+    { NS_VK_META,       GDK_Meta_R },
+
+    // Assume that Super or Hyper is always mapped to physical Win key.
+    { NS_VK_WIN,        GDK_Super_L },
+    { NS_VK_WIN,        GDK_Super_R },
+    { NS_VK_WIN,        GDK_Hyper_L },
+    { NS_VK_WIN,        GDK_Hyper_R },
+
+    // GTK's AltGraph key is similar to Mac's Option (Alt) key.  However,
+    // unfortunately, browsers on Mac are using NS_VK_ALT for it even though
+    // it's really different from Alt key on Windows.
+    // On the other hand, GTK's AltGrapsh keys are really different from
+    // Alt key.  However, there is no AltGrapsh key on Windows.  On Windows,
+    // both Ctrl and Alt keys are pressed internally when AltGr key is pressed.
+    // For some languages' users, AltGraph key is important, so, web
+    // applications on such locale may want to know AltGraph key press.
+    // Therefore, we should map AltGr keycode for them only on GTK.
+    { NS_VK_ALTGR,      GDK_ISO_Level3_Shift },
+    { NS_VK_ALTGR,      GDK_ISO_Level5_Shift },
+    // We assume that Mode_switch is always used for level3 shift.
+    { NS_VK_ALTGR,      GDK_Mode_switch },
+
+    { NS_VK_PAUSE,      GDK_Pause },
+    { NS_VK_CAPS_LOCK,  GDK_Caps_Lock },
+    { NS_VK_KANA,       GDK_Kana_Lock },
+    { NS_VK_KANA,       GDK_Kana_Shift },
+    { NS_VK_HANGUL,     GDK_Hangul },
+    // { NS_VK_JUNJA,      GDK_XXX },
+    // { NS_VK_FINAL,      GDK_XXX },
+    { NS_VK_HANJA,      GDK_Hangul_Hanja },
+    { NS_VK_KANJI,      GDK_Kanji },
+    { NS_VK_ESCAPE,     GDK_Escape },
+    { NS_VK_CONVERT,    GDK_Henkan },
+    { NS_VK_NONCONVERT, GDK_Muhenkan },
+    // { NS_VK_ACCEPT,     GDK_XXX },
+    // { NS_VK_MODECHANGE, GDK_XXX },
+    { NS_VK_SPACE,      GDK_space },
+    { NS_VK_PAGE_UP,    GDK_Page_Up },
+    { NS_VK_PAGE_DOWN,  GDK_Page_Down },
+    { NS_VK_END,        GDK_End },
+    { NS_VK_HOME,       GDK_Home },
+    { NS_VK_LEFT,       GDK_Left },
+    { NS_VK_UP,         GDK_Up },
+    { NS_VK_RIGHT,      GDK_Right },
+    { NS_VK_DOWN,       GDK_Down },
+    { NS_VK_SELECT,     GDK_Select },
+    { NS_VK_PRINT,      GDK_Print },
+    { NS_VK_EXECUTE,    GDK_Execute },
+    { NS_VK_PRINTSCREEN, GDK_Print },
+    { NS_VK_INSERT,     GDK_Insert },
+    { NS_VK_DELETE,     GDK_Delete },
+    { NS_VK_HELP,       GDK_Help },
+
+    // keypad keys
+    { NS_VK_LEFT,       GDK_KP_Left },
+    { NS_VK_RIGHT,      GDK_KP_Right },
+    { NS_VK_UP,         GDK_KP_Up },
+    { NS_VK_DOWN,       GDK_KP_Down },
+    { NS_VK_PAGE_UP,    GDK_KP_Page_Up },
+    // Not sure what these are
+    //{ NS_VK_,       GDK_KP_Prior },
+    //{ NS_VK_,        GDK_KP_Next },
+    { NS_VK_CLEAR,      GDK_KP_Begin }, // Num-unlocked 5
+    { NS_VK_PAGE_DOWN,  GDK_KP_Page_Down },
+    { NS_VK_HOME,       GDK_KP_Home },
+    { NS_VK_END,        GDK_KP_End },
+    { NS_VK_INSERT,     GDK_KP_Insert },
+    { NS_VK_DELETE,     GDK_KP_Delete },
+    { NS_VK_RETURN,     GDK_KP_Enter },
+
+    { NS_VK_NUM_LOCK,   GDK_Num_Lock },
+    { NS_VK_SCROLL_LOCK,GDK_Scroll_Lock },
+
+    // Function keys
+    { NS_VK_F1,         GDK_F1 },
+    { NS_VK_F2,         GDK_F2 },
+    { NS_VK_F3,         GDK_F3 },
+    { NS_VK_F4,         GDK_F4 },
+    { NS_VK_F5,         GDK_F5 },
+    { NS_VK_F6,         GDK_F6 },
+    { NS_VK_F7,         GDK_F7 },
+    { NS_VK_F8,         GDK_F8 },
+    { NS_VK_F9,         GDK_F9 },
+    { NS_VK_F10,        GDK_F10 },
+    { NS_VK_F11,        GDK_F11 },
+    { NS_VK_F12,        GDK_F12 },
+    { NS_VK_F13,        GDK_F13 },
+    { NS_VK_F14,        GDK_F14 },
+    { NS_VK_F15,        GDK_F15 },
+    { NS_VK_F16,        GDK_F16 },
+    { NS_VK_F17,        GDK_F17 },
+    { NS_VK_F18,        GDK_F18 },
+    { NS_VK_F19,        GDK_F19 },
+    { NS_VK_F20,        GDK_F20 },
+    { NS_VK_F21,        GDK_F21 },
+    { NS_VK_F22,        GDK_F22 },
+    { NS_VK_F23,        GDK_F23 },
+    { NS_VK_F24,        GDK_F24 },
+
+    // context menu key, keysym 0xff67, typically keycode 117 on 105-key (Microsoft) 
+    // x86 keyboards, located between right 'Windows' key and right Ctrl key
+    { NS_VK_CONTEXT_MENU, GDK_Menu },
+    { NS_VK_SLEEP,      GDK_Sleep },
+
+    { NS_VK_ATTN,       GDK_3270_Attn },
+    { NS_VK_CRSEL,      GDK_3270_CursorSelect },
+    { NS_VK_EXSEL,      GDK_3270_ExSelect },
+    { NS_VK_EREOF,      GDK_3270_EraseEOF },
+    { NS_VK_PLAY,       GDK_3270_Play },
+    //{ NS_VK_ZOOM,       GDK_XXX },
+    { NS_VK_PA1,        GDK_3270_PA1 },
+};
+
+static guint
+ConvertGeckoKeyNameToGDKKeyval(nsAString& aKeyName) {
+    NS_ConvertUTF16toUTF8 keyName(aKeyName);
+    ToUpperCase(keyName); // We want case-insensitive comparison with data
+                          // stored as uppercase.
+
+    uint32_t keyCode = 0;
+
+    uint32_t keyNameLength = keyName.Length();
+    const char* keyNameStr = keyName.get();
+    for (uint16_t i = 0; i < ArrayLength(gKeyCodes); ++i) {
+        if (keyNameLength == gKeyCodes[i].strlength &&
+            !nsCRT::strcmp(gKeyCodes[i].str, keyNameStr)) {
+            keyCode = gKeyCodes[i].keycode;
+            break;
+        }
+    }
+
+    // First, try to handle alphanumeric input, not listed in nsKeycodes:
+    // most likely, more letters will be getting typed in than things in
+    // the key list, so we will look through these first.
+
+    if (keyCode >= NS_VK_A && keyCode <= NS_VK_Z) {
+        // gdk and DOM both use the ASCII codes for these keys.
+        return keyCode;
+    }
+
+    // numbers
+    if (keyCode >= NS_VK_0 && keyCode <= NS_VK_9) {
+        // gdk and DOM both use the ASCII codes for these keys.
+        return keyCode - NS_VK_0 + GDK_0;
+    }
+
+    switch (keyCode) {
+        // keys in numpad
+        case NS_VK_MULTIPLY:  return GDK_KP_Multiply;
+        case NS_VK_ADD:       return GDK_KP_Add;
+        case NS_VK_SEPARATOR: return GDK_KP_Separator;
+        case NS_VK_SUBTRACT:  return GDK_KP_Subtract;
+        case NS_VK_DECIMAL:   return GDK_KP_Decimal;
+        case NS_VK_DIVIDE:    return GDK_KP_Divide;
+        case NS_VK_NUMPAD0:   return GDK_KP_0;
+        case NS_VK_NUMPAD1:   return GDK_KP_1;
+        case NS_VK_NUMPAD2:   return GDK_KP_2;
+        case NS_VK_NUMPAD3:   return GDK_KP_3;
+        case NS_VK_NUMPAD4:   return GDK_KP_4;
+        case NS_VK_NUMPAD5:   return GDK_KP_5;
+        case NS_VK_NUMPAD6:   return GDK_KP_6;
+        case NS_VK_NUMPAD7:   return GDK_KP_7;
+        case NS_VK_NUMPAD8:   return GDK_KP_8;
+        case NS_VK_NUMPAD9:   return GDK_KP_9;
+        // other prinable keys
+        case NS_VK_SPACE:               return GDK_space;
+        case NS_VK_COLON:               return GDK_colon;
+        case NS_VK_SEMICOLON:           return GDK_semicolon;
+        case NS_VK_LESS_THAN:           return GDK_less;
+        case NS_VK_EQUALS:              return GDK_equal;
+        case NS_VK_GREATER_THAN:        return GDK_greater;
+        case NS_VK_QUESTION_MARK:       return GDK_question;
+        case NS_VK_AT:                  return GDK_at;
+        case NS_VK_CIRCUMFLEX:          return GDK_asciicircum;
+        case NS_VK_EXCLAMATION:         return GDK_exclam;
+        case NS_VK_DOUBLE_QUOTE:        return GDK_quotedbl;
+        case NS_VK_HASH:                return GDK_numbersign;
+        case NS_VK_DOLLAR:              return GDK_dollar;
+        case NS_VK_PERCENT:             return GDK_percent;
+        case NS_VK_AMPERSAND:           return GDK_ampersand;
+        case NS_VK_UNDERSCORE:          return GDK_underscore;
+        case NS_VK_OPEN_PAREN:          return GDK_parenleft;
+        case NS_VK_CLOSE_PAREN:         return GDK_parenright;
+        case NS_VK_ASTERISK:            return GDK_asterisk;
+        case NS_VK_PLUS:                return GDK_plus;
+        case NS_VK_PIPE:                return GDK_bar;
+        case NS_VK_HYPHEN_MINUS:        return GDK_minus;
+        case NS_VK_OPEN_CURLY_BRACKET:  return GDK_braceleft;
+        case NS_VK_CLOSE_CURLY_BRACKET: return GDK_braceright;
+        case NS_VK_TILDE:               return GDK_asciitilde;
+        case NS_VK_COMMA:               return GDK_comma;
+        case NS_VK_PERIOD:              return GDK_period;
+        case NS_VK_SLASH:               return GDK_slash;
+        case NS_VK_BACK_QUOTE:          return GDK_grave;
+        case NS_VK_OPEN_BRACKET:        return GDK_bracketleft;
+        case NS_VK_BACK_SLASH:          return GDK_backslash;
+        case NS_VK_CLOSE_BRACKET:       return GDK_bracketright;
+        case NS_VK_QUOTE:               return GDK_apostrophe;
+    }
+
+    // misc other things
+    for (uint32_t i = 0; i < ArrayLength(gKeyPairs); ++i) {
+        if (gKeyPairs[i].DOMKeyCode == keyCode) {
+            return gKeyPairs[i].GDKKeyval;
+        }
+    }
+
+    return 0;
+}
+
+class nsMenuItemUncheckSiblingsRunnable final : public Runnable {
+public:
+    NS_IMETHODIMP Run() {
+        if (mMenuItem) {
+            static_cast<nsMenuItem* >(mMenuItem.get())->UncheckSiblings();
+        }
+        return NS_OK;
+    }
+
+    nsMenuItemUncheckSiblingsRunnable(nsMenuItem* aMenuItem) :
+        mMenuItem(aMenuItem) { };
+
+private:
+    nsWeakMenuObject mMenuItem;
+};
+
+bool
+nsMenuItem::IsCheckboxOrRadioItem() const {
+    return mType == eMenuItemType_Radio ||
+           mType == eMenuItemType_CheckBox;
+}
+
+/* static */ void
+nsMenuItem::item_activated_cb(DbusmenuMenuitem* menuitem,
+                              guint timestamp,
+                              gpointer user_data) {
+    nsMenuItem* item = static_cast<nsMenuItem* >(user_data);
+    item->Activate(timestamp);
+}
+
+void
+nsMenuItem::Activate(uint32_t aTimestamp) {
+    GdkWindow* window = gtk_widget_get_window(MenuBar()->TopLevelWindow());
+    gdk_x11_window_set_user_time(
+        window, std::min(aTimestamp, gdk_x11_get_server_time(window)));
+
+    // We do this to avoid mutating our view of the menu until
+    // after we have finished
+    nsNativeMenuDocListener::BlockUpdatesScope updatesBlocker;
+
+    if (!ContentNode()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::autocheck,
+                                    nsGkAtoms::_false, eCaseMatters) &&
+        (mType == eMenuItemType_CheckBox ||
+         (mType == eMenuItemType_Radio && !mIsChecked))) {
+        ContentNode()->SetAttr(kNameSpaceID_None, nsGkAtoms::checked,
+                               mIsChecked ?
+                               NS_LITERAL_STRING("false") :  NS_LITERAL_STRING("true"),
+                               true);
+    }
+
+    nsIDocument* doc = ContentNode()->OwnerDoc();
+    nsCOMPtr<nsIDOMEventTarget> target = do_QueryInterface(ContentNode());
+    nsCOMPtr<nsIDOMDocument> domDoc = do_QueryInterface(doc);
+    if (domDoc && target) {
+        nsCOMPtr<nsIDOMEvent> event;
+        domDoc->CreateEvent(NS_LITERAL_STRING("xulcommandevent"),
+                            getter_AddRefs(event));
+        nsCOMPtr<nsIDOMXULCommandEvent> command = do_QueryInterface(event);
+        if (command) {
+            command->InitCommandEvent(NS_LITERAL_STRING("command"),
+                                      true, true, doc->GetInnerWindow(), 0,
+                                      false, false, false, false, nullptr);
+
+            event->SetTrusted(true);
+            bool dummy;
+            target->DispatchEvent(event, &dummy);
+        }
+    }
+
+    // This kinda sucks, but Unity doesn't send a closed event
+    // after activating a menuitem
+    nsMenuObject* ancestor = Parent();
+    while (ancestor && ancestor->Type() == eType_Menu) {
+        static_cast<nsMenu* >(ancestor)->OnClose();
+        ancestor = ancestor->Parent();
+    }
+}
+
+void
+nsMenuItem::CopyAttrFromNodeIfExists(nsIContent* aContent, nsIAtom* aAttribute) {
+    nsAutoString value;
+    if (aContent->GetAttr(kNameSpaceID_None, aAttribute, value)) {
+        ContentNode()->SetAttr(kNameSpaceID_None, aAttribute, value, true);
+    }
+}
+
+void
+nsMenuItem::UpdateState() {
+    if (!IsCheckboxOrRadioItem()) {
+        return;
+    }
+
+    mIsChecked = ContentNode()->AttrValueIs(kNameSpaceID_None,
+                                            nsGkAtoms::checked,
+                                            nsGkAtoms::_true,
+                                            eCaseMatters);
+    dbusmenu_menuitem_property_set_int(GetNativeData(),
+                                       DBUSMENU_MENUITEM_PROP_TOGGLE_STATE,
+                                       mIsChecked ?
+                                         DBUSMENU_MENUITEM_TOGGLE_STATE_CHECKED : 
+                                         DBUSMENU_MENUITEM_TOGGLE_STATE_UNCHECKED);
+}
+
+void
+nsMenuItem::UpdateTypeAndState() {
+    static nsIContent::AttrValuesArray attrs[] =
+        { &nsGkAtoms::checkbox, &nsGkAtoms::radio, nullptr };
+    int32_t type = ContentNode()->FindAttrValueIn(kNameSpaceID_None,
+                                                  nsGkAtoms::type,
+                                                  attrs, eCaseMatters);
+
+    if (type >= 0 && type < 2) {
+        if (type == 0) {
+            dbusmenu_menuitem_property_set(GetNativeData(),
+                                           DBUSMENU_MENUITEM_PROP_TOGGLE_TYPE,
+                                           DBUSMENU_MENUITEM_TOGGLE_CHECK);
+            mType = eMenuItemType_CheckBox;
+        } else if (type == 1) {
+            dbusmenu_menuitem_property_set(GetNativeData(),
+                                           DBUSMENU_MENUITEM_PROP_TOGGLE_TYPE,
+                                           DBUSMENU_MENUITEM_TOGGLE_RADIO);
+            mType = eMenuItemType_Radio;
+        }
+
+        UpdateState();
+    } else {
+        dbusmenu_menuitem_property_remove(GetNativeData(),
+                                          DBUSMENU_MENUITEM_PROP_TOGGLE_TYPE);
+        dbusmenu_menuitem_property_remove(GetNativeData(),
+                                          DBUSMENU_MENUITEM_PROP_TOGGLE_STATE);
+        mType = eMenuItemType_Normal;
+    }
+}
+
+void
+nsMenuItem::UpdateAccel() {
+    nsIDocument* doc = ContentNode()->GetUncomposedDoc();
+    if (doc) {
+        nsCOMPtr<nsIContent> oldKeyContent;
+        oldKeyContent.swap(mKeyContent);
+
+        nsAutoString key;
+        ContentNode()->GetAttr(kNameSpaceID_None, nsGkAtoms::key, key);
+        if (!key.IsEmpty()) {
+            mKeyContent = doc->GetElementById(key);
+        }
+
+        if (mKeyContent != oldKeyContent) {
+            if (oldKeyContent) {
+                DocListener()->UnregisterForContentChanges(oldKeyContent);
+            }
+            if (mKeyContent) {
+                DocListener()->RegisterForContentChanges(mKeyContent, this);
+            }
+        }
+    }
+
+    if (!mKeyContent) {
+        dbusmenu_menuitem_property_remove(GetNativeData(),
+                                          DBUSMENU_MENUITEM_PROP_SHORTCUT);
+        return;
+    }
+
+    nsAutoString modifiers;
+    mKeyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::modifiers, modifiers);
+
+    uint32_t modifier = 0;
+
+    if (!modifiers.IsEmpty()) {
+        char* str = ToNewUTF8String(modifiers);
+        char* token = strtok(str, ", \t");
+        while(token) {
+            if (nsCRT::strcmp(token, "shift") == 0) {
+                modifier |= GDK_SHIFT_MASK;
+            } else if (nsCRT::strcmp(token, "alt") == 0) {
+                modifier |= GDK_MOD1_MASK;
+            } else if (nsCRT::strcmp(token, "meta") == 0) {
+                modifier |= GDK_META_MASK;
+            } else if (nsCRT::strcmp(token, "control") == 0) {
+                modifier |= GDK_CONTROL_MASK;
+            } else if (nsCRT::strcmp(token, "accel") == 0) {
+                int32_t accel = Preferences::GetInt("ui.key.accelKey");
+                if (accel == nsIDOMKeyEvent::DOM_VK_META) {
+                    modifier |= GDK_META_MASK;
+                } else if (accel == nsIDOMKeyEvent::DOM_VK_ALT) {
+                    modifier |= GDK_MOD1_MASK;
+                } else {
+                    modifier |= GDK_CONTROL_MASK;
+                }
+            }
+
+            token = strtok(nullptr, ", \t");
+        }
+
+        free(str);
+    }
+
+    nsAutoString keyStr;
+    mKeyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::key, keyStr);
+
+    guint key = 0;
+    if (!keyStr.IsEmpty()) {
+        key = gdk_unicode_to_keyval(*keyStr.BeginReading());
+    }
+
+    if (key == 0) {
+        mKeyContent->GetAttr(kNameSpaceID_None, nsGkAtoms::keycode, keyStr);
+        if (!keyStr.IsEmpty()) {
+            key = ConvertGeckoKeyNameToGDKKeyval(keyStr);
+        }
+    }
+
+    if (key == 0) {
+        key = GDK_VoidSymbol;
+    }
+
+    if (key != GDK_VoidSymbol) {
+        dbusmenu_menuitem_property_set_shortcut(GetNativeData(), key,
+                                                static_cast<GdkModifierType>(modifier));
+    } else {
+        dbusmenu_menuitem_property_remove(GetNativeData(),
+                                          DBUSMENU_MENUITEM_PROP_SHORTCUT);
+    }
+}
+
+nsMenuBar*
+nsMenuItem::MenuBar() {
+    nsMenuObject* tmp = this;
+    while (tmp->Parent()) {
+        tmp = tmp->Parent();
+    }
+
+    MOZ_ASSERT(tmp->Type() == eType_MenuBar, "The top-level should be a menubar");
+
+    return static_cast<nsMenuBar* >(tmp);
+}
+
+void
+nsMenuItem::UncheckSiblings() {
+    if (!ContentNode()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                    nsGkAtoms::radio, eCaseMatters)) {
+        // If we're not a radio button, we don't care
+        return;
+    }
+
+    nsAutoString name;
+    ContentNode()->GetAttr(kNameSpaceID_None, nsGkAtoms::name, name);
+
+    nsIContent* parent = ContentNode()->GetParent();
+    if (!parent) {
+        return;
+    }
+
+    uint32_t count = parent->GetChildCount();
+    for (uint32_t i = 0; i < count; ++i) {
+        nsIContent* sibling = parent->GetChildAt(i);
+
+        nsAutoString otherName;
+        sibling->GetAttr(kNameSpaceID_None, nsGkAtoms::name, otherName);
+
+        if (sibling != ContentNode() && otherName == name && 
+            sibling->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
+                                 nsGkAtoms::radio, eCaseMatters)) {
+            sibling->UnsetAttr(kNameSpaceID_None, nsGkAtoms::checked, true);
+        }
+    }
+}
+
+void
+nsMenuItem::InitializeNativeData() {
+    g_signal_connect(G_OBJECT(GetNativeData()),
+                     DBUSMENU_MENUITEM_SIGNAL_ITEM_ACTIVATED,
+                     G_CALLBACK(item_activated_cb), this);
+    mNeedsUpdate = true;
+}
+
+void
+nsMenuItem::UpdateContentAttributes() {
+    nsIDocument* doc = ContentNode()->GetUncomposedDoc();
+    if (!doc) {
+        return;
+    }
+
+    nsAutoString command;
+    ContentNode()->GetAttr(kNameSpaceID_None, nsGkAtoms::command, command);
+    if (command.IsEmpty()) {
+        return;
+    }
+
+    nsCOMPtr<nsIContent> commandContent = doc->GetElementById(command);
+    if (!commandContent) {
+        return;
+    }
+
+    if (commandContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
+                                    nsGkAtoms::_true, eCaseMatters)) {
+        ContentNode()->SetAttr(kNameSpaceID_None, nsGkAtoms::disabled,
+                               NS_LITERAL_STRING("true"), true);
+    } else {
+        ContentNode()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::disabled, true);
+    }
+
+    CopyAttrFromNodeIfExists(commandContent, nsGkAtoms::checked);
+    CopyAttrFromNodeIfExists(commandContent, nsGkAtoms::accesskey);
+    CopyAttrFromNodeIfExists(commandContent, nsGkAtoms::label);
+    CopyAttrFromNodeIfExists(commandContent, nsGkAtoms::hidden);
+}
+
+void
+nsMenuItem::Update(nsStyleContext* aStyleContext) {
+    if (mNeedsUpdate) {
+        mNeedsUpdate = false;
+
+        UpdateTypeAndState();
+        UpdateAccel();
+        UpdateLabel();
+        UpdateSensitivity();
+    }
+
+    UpdateVisibility(aStyleContext);
+    UpdateIcon(aStyleContext);
+}
+
+bool
+nsMenuItem::IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const {
+    return nsCRT::strcmp(dbusmenu_menuitem_property_get(aNativeData,
+                                                        DBUSMENU_MENUITEM_PROP_TYPE),
+                         "separator") != 0;
+}
+
+nsMenuObject::PropertyFlags
+nsMenuItem::SupportedProperties() const {
+    return static_cast<nsMenuObject::PropertyFlags>(
+        nsMenuObject::ePropLabel |
+        nsMenuObject::ePropEnabled |
+        nsMenuObject::ePropVisible |
+        nsMenuObject::ePropIconData |
+        nsMenuObject::ePropShortcut |
+        nsMenuObject::ePropToggleType |
+        nsMenuObject::ePropToggleState
+    );
+}
+
+void
+nsMenuItem::OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) {
+    MOZ_ASSERT(aContent == ContentNode() || aContent == mKeyContent,
+               "Received an event that wasn't meant for us!");
+
+    if (aContent == ContentNode() && aAttribute == nsGkAtoms::checked &&
+        aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::checked,
+                              nsGkAtoms::_true, eCaseMatters)) {
+        nsContentUtils::AddScriptRunner(
+            new nsMenuItemUncheckSiblingsRunnable(this));
+    }
+
+    if (mNeedsUpdate) {
+        return;
+    }
+
+    if (!Parent()->IsBeingDisplayed()) {
+        mNeedsUpdate = true;
+        return;
+    }
+
+    if (aContent == ContentNode()) {
+        if (aAttribute == nsGkAtoms::key) {
+            UpdateAccel();
+        } else if (aAttribute == nsGkAtoms::label ||
+                   aAttribute == nsGkAtoms::accesskey ||
+                   aAttribute == nsGkAtoms::crop) {
+            UpdateLabel();
+        } else if (aAttribute == nsGkAtoms::disabled) {
+            UpdateSensitivity();
+        } else if (aAttribute == nsGkAtoms::type) {
+            UpdateTypeAndState();
+        } else if (aAttribute == nsGkAtoms::checked) {
+            UpdateState();
+        } else if (aAttribute == nsGkAtoms::hidden ||
+                   aAttribute == nsGkAtoms::collapsed) {
+            RefPtr<nsStyleContext> sc = GetStyleContext();
+            UpdateVisibility(sc);
+        } else if (aAttribute == nsGkAtoms::image) {
+            RefPtr<nsStyleContext> sc = GetStyleContext();
+            UpdateIcon(sc);
+        }
+    } else if (aContent == mKeyContent &&
+               (aAttribute == nsGkAtoms::key ||
+                aAttribute == nsGkAtoms::keycode ||
+                aAttribute == nsGkAtoms::modifiers)) {
+        UpdateAccel();
+    }
+}
+
+nsMenuItem::nsMenuItem(nsMenuContainer* aParent, nsIContent* aContent) :
+    nsMenuObject(aParent, aContent),
+    mType(eMenuItemType_Normal),
+    mIsChecked(false),
+    mNeedsUpdate(false) {
+    MOZ_COUNT_CTOR(nsMenuItem);
+}
+
+nsMenuItem::~nsMenuItem() {
+    if (DocListener() && mKeyContent) {
+        DocListener()->UnregisterForContentChanges(mKeyContent);
+    }
+
+    if (GetNativeData()) {
+        g_signal_handlers_disconnect_by_func(GetNativeData(),
+                                             FuncToGpointer(item_activated_cb),
+                                             this);
+    }
+
+    MOZ_COUNT_DTOR(nsMenuItem);
+}
+
+nsMenuObject::EType
+nsMenuItem::Type() const {
+    return eType_MenuItem;
+}
diff --git a/widget/gtk/nsMenuItem.h b/widget/gtk/nsMenuItem.h
new file mode 100644
index 000000000..e81b6e308
--- /dev/null
+++ b/widget/gtk/nsMenuItem.h
@@ -0,0 +1,77 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenuItem_h__
+#define __nsMenuItem_h__
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+
+#include "nsDbusmenu.h"
+#include "nsMenuObject.h"
+
+#include <glib.h>
+
+class nsIAtom;
+class nsIContent;
+class nsStyleContext;
+class nsMenuBar;
+class nsMenuContainer;
+
+/*
+ * This class represents 3 main classes of menuitems: labels, checkboxes and
+ * radio buttons (with/without an icon)
+ */
+class nsMenuItem final : public nsMenuObject {
+public:
+    nsMenuItem(nsMenuContainer* aParent, nsIContent* aContent);
+    ~nsMenuItem() override;
+
+    nsMenuObject::EType Type() const override;
+
+private:
+    friend class nsMenuItemUncheckSiblingsRunnable;
+
+    enum {
+        eMenuItemFlag_ToggleState = (1 << 0)
+    };
+
+    enum EMenuItemType {
+        eMenuItemType_Normal,
+        eMenuItemType_Radio,
+        eMenuItemType_CheckBox
+    };
+
+    bool IsCheckboxOrRadioItem() const;
+
+    static void item_activated_cb(DbusmenuMenuitem* menuitem,
+                                  guint timestamp,
+                                  gpointer user_data);
+    void Activate(uint32_t aTimestamp);
+
+    void CopyAttrFromNodeIfExists(nsIContent* aContent, nsIAtom* aAtom);
+    void UpdateState();
+    void UpdateTypeAndState();
+    void UpdateAccel();
+    nsMenuBar* MenuBar();
+    void UncheckSiblings();
+
+    void InitializeNativeData() override;
+    void UpdateContentAttributes() override;
+    void Update(nsStyleContext* aStyleContext) override;
+    bool IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const override;
+    nsMenuObject::PropertyFlags SupportedProperties() const override;
+
+    void OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) override;
+
+    EMenuItemType mType;
+
+    bool mIsChecked;
+
+    bool mNeedsUpdate;
+
+    nsCOMPtr<nsIContent> mKeyContent;
+};
+
+#endif /* __nsMenuItem_h__ */
diff --git a/widget/gtk/nsMenuObject.cpp b/widget/gtk/nsMenuObject.cpp
new file mode 100644
index 000000000..58d1716fd
--- /dev/null
+++ b/widget/gtk/nsMenuObject.cpp
@@ -0,0 +1,634 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ *  License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImageOps.h"
+#include "imgIContainer.h"
+#include "imgINotificationObserver.h"
+#include "imgLoader.h"
+#include "imgRequestProxy.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/Preferences.h"
+#include "nsAttrValue.h"
+#include "nsComputedDOMStyle.h"
+#include "nsContentUtils.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsIContentPolicy.h"
+#include "nsIDocument.h"
+#include "nsILoadGroup.h"
+#include "nsImageToPixbuf.h"
+#include "nsIPresShell.h"
+#include "nsIURI.h"
+#include "nsNetUtil.h"
+#include "nsPresContext.h"
+#include "nsRect.h"
+#include "nsServiceManagerUtils.h"
+#include "nsString.h"
+#include "nsStyleConsts.h"
+#include "nsStyleContext.h"
+#include "nsStyleStruct.h"
+#include "nsUnicharUtils.h"
+
+#include "nsMenuContainer.h"
+#include "nsNativeMenuAtoms.h"
+#include "nsNativeMenuDocListener.h"
+
+#include <gdk/gdk.h>
+#include <glib-object.h>
+#include <pango/pango.h>
+
+#include "nsMenuObject.h"
+
+// X11's None clashes with StyleDisplay::None
+#include "X11UndefineNone.h"
+
+#undef None
+
+using namespace mozilla;
+using mozilla::image::ImageOps;
+
+#define MAX_WIDTH 350000
+
+const char* gPropertyStrings[] = {
+#define DBUSMENU_PROPERTY(e, s, b) s,
+    DBUSMENU_PROPERTIES
+#undef DBUSMENU_PROPERTY
+    nullptr
+};
+
+nsWeakMenuObject* nsWeakMenuObject::sHead;
+PangoLayout* gPangoLayout = nullptr;
+
+class nsMenuObjectIconLoader final : public imgINotificationObserver {
+public:
+    NS_DECL_ISUPPORTS
+    NS_DECL_IMGINOTIFICATIONOBSERVER
+
+    nsMenuObjectIconLoader(nsMenuObject* aOwner) : mOwner(aOwner) { };
+
+    void LoadIcon(nsStyleContext* aStyleContext);
+    void Destroy();
+
+private:
+    ~nsMenuObjectIconLoader() { };
+
+    nsMenuObject* mOwner;
+    RefPtr<imgRequestProxy> mImageRequest;
+    nsCOMPtr<nsIURI> mURI;
+    nsIntRect mImageRect;
+};
+
+NS_IMPL_ISUPPORTS(nsMenuObjectIconLoader, imgINotificationObserver)
+
+NS_IMETHODIMP
+nsMenuObjectIconLoader::Notify(imgIRequest* aProxy,
+                               int32_t aType, const nsIntRect* aRect) {
+    if (!mOwner) {
+        return NS_OK;
+    }
+
+    if (aProxy != mImageRequest) {
+        return NS_ERROR_FAILURE;
+    }
+
+    if (aType == imgINotificationObserver::LOAD_COMPLETE) {
+        uint32_t status = imgIRequest::STATUS_ERROR;
+        if (NS_FAILED(mImageRequest->GetImageStatus(&status)) ||
+            (status & imgIRequest::STATUS_ERROR)) {
+            mImageRequest->Cancel(NS_BINDING_ABORTED);
+            mImageRequest = nullptr;
+            return NS_ERROR_FAILURE;
+        }
+
+        nsCOMPtr<imgIContainer> image;
+        mImageRequest->GetImage(getter_AddRefs(image));
+        MOZ_ASSERT(image);
+
+        // Ask the image to decode at its intrinsic size.
+        int32_t width = 0, height = 0;
+        image->GetWidth(&width);
+        image->GetHeight(&height);
+        image->RequestDecodeForSize(nsIntSize(width, height), imgIContainer::FLAG_NONE);
+        return NS_OK;
+    }
+
+    if (aType == imgINotificationObserver::DECODE_COMPLETE) {
+        mImageRequest->Cancel(NS_BINDING_ABORTED);
+        mImageRequest = nullptr;
+        return NS_OK;
+    }
+
+    if (aType != imgINotificationObserver::FRAME_COMPLETE) {
+        return NS_OK;
+    }
+
+    nsCOMPtr<imgIContainer> img;
+    mImageRequest->GetImage(getter_AddRefs(img));
+    if (!img) {
+        return NS_ERROR_FAILURE;
+    }
+
+    if (!mImageRect.IsEmpty()) {
+        img = ImageOps::Clip(img, mImageRect);
+    }
+
+    int32_t width, height;
+    img->GetWidth(&width);
+    img->GetHeight(&height);
+
+    if (width <= 0 || height <= 0) {
+        mOwner->ClearIcon();
+        return NS_OK;
+    }
+
+    if (width > 100 || height > 100) {
+        // The icon data needs to go across DBus. Make sure the icon
+        // data isn't too large, else our connection gets terminated and
+        // GDbus helpfully aborts the application. Thank you :)
+        NS_WARNING("Icon data too large");
+        mOwner->ClearIcon();
+        return NS_OK;
+    }
+
+    GdkPixbuf* pixbuf = nsImageToPixbuf::ImageToPixbuf(img);
+    if (pixbuf) {
+        dbusmenu_menuitem_property_set_image(mOwner->GetNativeData(),
+                                             DBUSMENU_MENUITEM_PROP_ICON_DATA,
+                                             pixbuf);
+        g_object_unref(pixbuf);
+    }
+
+    return NS_OK;
+}
+
+void
+nsMenuObjectIconLoader::LoadIcon(nsStyleContext* aStyleContext) {
+    nsIDocument* doc = mOwner->ContentNode()->OwnerDoc();
+
+    nsCOMPtr<nsIURI> uri;
+    nsIntRect imageRect;
+    imgRequestProxy* imageRequest = nullptr;
+
+    nsAutoString uriString;
+    if (mOwner->ContentNode()->GetAttr(kNameSpaceID_None, nsGkAtoms::image,
+                                       uriString)) {
+        NS_NewURI(getter_AddRefs(uri), uriString);
+    } else {
+        nsIPresShell* shell = doc->GetShell();
+        if (!shell) {
+            return;
+        }
+
+        nsPresContext* pc = shell->GetPresContext();
+        if (!pc || !aStyleContext) {
+            return;
+        }
+
+        const nsStyleList* list = aStyleContext->StyleList();
+        imageRequest = list->GetListStyleImage();
+        if (imageRequest) {
+            imageRequest->GetURI(getter_AddRefs(uri));
+            imageRect = list->mImageRegion.ToNearestPixels(
+                            pc->AppUnitsPerDevPixel());
+        }
+    }
+
+    if (!uri) {
+        mOwner->ClearIcon();
+        mURI = nullptr;
+
+        if (mImageRequest) {
+            mImageRequest->Cancel(NS_BINDING_ABORTED);
+            mImageRequest = nullptr;
+        }
+
+        return;
+    }
+
+    bool same;
+    if (mURI && NS_SUCCEEDED(mURI->Equals(uri, &same)) && same && 
+        (!imageRequest || imageRect == mImageRect)) {
+        return;
+    }
+
+    if (mImageRequest) {
+        mImageRequest->Cancel(NS_BINDING_ABORTED);
+        mImageRequest = nullptr;
+    }
+
+    mURI = uri;
+
+    if (imageRequest) {
+        mImageRect = imageRect;
+        imageRequest->Clone(this, getter_AddRefs(mImageRequest));
+    } else {
+        mImageRect.SetEmpty();
+        nsCOMPtr<nsILoadGroup> loadGroup = doc->GetDocumentLoadGroup();
+        RefPtr<imgLoader> loader =
+            nsContentUtils::GetImgLoaderForDocument(doc);
+        if (!loader || !loadGroup) {
+            NS_WARNING("Failed to get loader or load group for image load");
+            return;
+        }
+
+        loader->LoadImage(uri, nullptr, nullptr, mozilla::net::RP_Unset,
+                          nullptr, loadGroup, this, nullptr, nullptr,
+                          nsIRequest::LOAD_NORMAL, nullptr,
+                          nsIContentPolicy::TYPE_IMAGE, EmptyString(),
+                          getter_AddRefs(mImageRequest));
+    }
+}
+
+void
+nsMenuObjectIconLoader::Destroy() {
+    if (mImageRequest) {
+        mImageRequest->CancelAndForgetObserver(NS_BINDING_ABORTED);
+        mImageRequest = nullptr;
+    }
+
+    mOwner = nullptr;
+}
+
+static int
+CalculateTextWidth(const nsAString& aText) {
+    if (!gPangoLayout) {
+        PangoFontMap* fontmap = pango_cairo_font_map_get_default();
+        PangoContext* ctx = pango_font_map_create_context(fontmap);
+        gPangoLayout = pango_layout_new(ctx);
+        g_object_unref(ctx);
+    }
+
+    pango_layout_set_text(gPangoLayout, NS_ConvertUTF16toUTF8(aText).get(), -1);
+
+    int width, dummy;
+    pango_layout_get_size(gPangoLayout, &width, &dummy);
+
+    return width;
+}
+
+static const nsDependentString
+GetEllipsis() {
+    static char16_t sBuf[4] = { 0, 0, 0, 0 };
+    if (!sBuf[0]) {
+        nsAdoptingString ellipsis = Preferences::GetLocalizedString("intl.ellipsis");
+        if (!ellipsis.IsEmpty()) {
+            uint32_t l = ellipsis.Length();
+            const nsAdoptingString::char_type* c = ellipsis.BeginReading();
+            uint32_t i = 0;
+            while (i < 3 && i < l) {
+                sBuf[i++] =* (c++);
+            }
+        } else {
+            sBuf[0] = '.';
+            sBuf[1] = '.';
+            sBuf[2] = '.';
+        }
+    }
+
+    return nsDependentString(sBuf);
+}
+
+static int
+GetEllipsisWidth() {
+    static int sEllipsisWidth = -1;
+
+    if (sEllipsisWidth == -1) {
+        sEllipsisWidth = CalculateTextWidth(GetEllipsis());
+    }
+
+    return sEllipsisWidth;
+}
+
+nsMenuObject::nsMenuObject(nsMenuContainer* aParent, nsIContent* aContent) :
+    mContent(aContent),
+    mListener(aParent->DocListener()),
+    mParent(aParent),
+    mNativeData(nullptr) {
+    MOZ_ASSERT(mContent);
+    MOZ_ASSERT(mListener);
+    MOZ_ASSERT(mParent);
+}
+
+nsMenuObject::nsMenuObject(nsNativeMenuDocListener* aListener,
+                           nsIContent* aContent) :
+    mContent(aContent),
+    mListener(aListener),
+    mParent(nullptr),
+    mNativeData(nullptr) {
+    MOZ_ASSERT(mContent);
+    MOZ_ASSERT(mListener);
+}
+
+void
+nsMenuObject::UpdateLabel() {
+    // Goanna stores the label and access key in separate attributes
+    // so we need to convert label="Foo_Bar"/accesskey="F" in to
+    // label="_Foo__Bar" for dbusmenu
+
+    nsAutoString label;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::label, label);
+
+    nsAutoString accesskey;
+    mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::accesskey, accesskey);
+
+    const nsAutoString::char_type* akey = accesskey.BeginReading();
+    char16_t keyLower = ToLowerCase(*akey);
+    char16_t keyUpper = ToUpperCase(*akey);
+
+    const nsAutoString::char_type* iter = label.BeginReading();
+    const nsAutoString::char_type* end = label.EndReading();
+    uint32_t length = label.Length();
+    uint32_t pos = 0;
+    bool foundAccessKey = false;
+
+    while (iter != end) {
+        if (*iter != char16_t('_')) {
+            if ((*iter != keyLower &&* iter != keyUpper) || foundAccessKey) {
+                ++iter;
+                ++pos;
+                continue;
+            }
+            foundAccessKey = true;
+        }
+
+        label.SetLength(++length);
+
+        iter = label.BeginReading() + pos;
+        end = label.EndReading();
+        nsAutoString::char_type* cur = label.BeginWriting() + pos;
+
+        memmove(cur + 1, cur, (length - 1 - pos)*  sizeof(nsAutoString::char_type));
+       * cur = nsAutoString::char_type('_');
+
+        iter += 2;
+        pos += 2;
+    }
+
+    if (CalculateTextWidth(label) <= MAX_WIDTH) {
+        dbusmenu_menuitem_property_set(mNativeData,
+                                       DBUSMENU_MENUITEM_PROP_LABEL,
+                                       NS_ConvertUTF16toUTF8(label).get());
+        return;
+    }
+
+    // This sucks.
+    // This should be done at the point where the menu is drawn (hello Unity),
+    // but unfortunately it doesn't do that and will happily fill your entire
+    // screen width with a menu if you have a bookmark with a really long title.
+    // This leaves us with no other option but to ellipsize here, with no proper
+    // knowledge of Unity's render path, font size etc. This is better than nothing
+    nsAutoString truncated;
+    int target = MAX_WIDTH - GetEllipsisWidth();
+    length = label.Length();
+
+    static nsIContent::AttrValuesArray strings[] = {
+        &nsGkAtoms::left, &nsGkAtoms::start,
+        &nsGkAtoms::center, &nsGkAtoms::right,
+        &nsGkAtoms::end, nullptr
+    };
+
+    int32_t type = mContent->FindAttrValueIn(kNameSpaceID_None,
+                                             nsGkAtoms::crop,
+                                             strings, eCaseMatters);
+
+    switch (type) {
+        case 0:
+        case 1:
+            // FIXME: Implement left cropping
+        case 2:
+            // FIXME: Implement center cropping
+        case 3:
+        case 4:
+        default:
+            for (uint32_t i = 0; i < length; i++) {
+                truncated.Append(label.CharAt(i));
+                if (CalculateTextWidth(truncated) > target) {
+                    break;
+                }
+            }
+
+            truncated.Append(GetEllipsis());
+    }
+
+    dbusmenu_menuitem_property_set(mNativeData,
+                                   DBUSMENU_MENUITEM_PROP_LABEL,
+                                   NS_ConvertUTF16toUTF8(truncated).get());
+}
+
+void
+nsMenuObject::UpdateVisibility(nsStyleContext* aStyleContext) {
+    bool vis = true;
+
+    if (aStyleContext &&
+        (aStyleContext->StyleDisplay()->mDisplay == StyleDisplay::None ||
+         aStyleContext->StyleVisibility()->mVisible ==
+            NS_STYLE_VISIBILITY_COLLAPSE)) {
+        vis = false;
+    }
+
+    dbusmenu_menuitem_property_set_bool(mNativeData,
+                                        DBUSMENU_MENUITEM_PROP_VISIBLE,
+                                        vis);
+}
+
+void
+nsMenuObject::UpdateSensitivity() {
+    bool disabled = mContent->AttrValueIs(kNameSpaceID_None,
+                                          nsGkAtoms::disabled,
+                                          nsGkAtoms::_true, eCaseMatters);
+
+    dbusmenu_menuitem_property_set_bool(mNativeData,
+                                        DBUSMENU_MENUITEM_PROP_ENABLED,
+                                        !disabled);
+
+}
+
+void
+nsMenuObject::UpdateIcon(nsStyleContext* aStyleContext) {
+    if (ShouldShowIcon()) {
+        if (!mIconLoader) {
+            mIconLoader = new nsMenuObjectIconLoader(this);
+        }
+
+        mIconLoader->LoadIcon(aStyleContext);
+    } else {
+        if (mIconLoader) {
+            mIconLoader->Destroy();
+            mIconLoader = nullptr;
+        }
+
+        ClearIcon();
+    }
+}
+
+already_AddRefed<nsStyleContext>
+nsMenuObject::GetStyleContext() {
+    nsIPresShell* shell = mContent->OwnerDoc()->GetShell();
+    if (!shell) {
+        return nullptr;
+    }
+
+    RefPtr<nsStyleContext> sc =
+        nsComputedDOMStyle::GetStyleContextForElementNoFlush(
+            mContent->AsElement(), nullptr, shell);
+
+    return sc.forget();
+}
+
+void
+nsMenuObject::InitializeNativeData() {
+}
+
+nsMenuObject::PropertyFlags
+nsMenuObject::SupportedProperties() const {
+    return static_cast<nsMenuObject::PropertyFlags>(0);
+}
+
+bool
+nsMenuObject::IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const {
+    return true;
+}
+
+void
+nsMenuObject::UpdateContentAttributes() {
+}
+
+void
+nsMenuObject::Update(nsStyleContext* aStyleContext) {
+}
+
+bool
+nsMenuObject::ShouldShowIcon() const {
+    // Ideally we want to know the visibility of the anonymous XUL image in
+    // our menuitem, but this isn't created because we don't have a frame.
+    // The following works by default (because xul.css hides images in menuitems
+    // that don't have the "menuitem-with-favicon" class). It's possible a third
+    // party theme could override this, but, oh well...
+    const nsAttrValue* classes = mContent->AsElement()->GetClasses();
+    if (!classes) {
+        return false;
+    }
+
+    for (uint32_t i = 0; i < classes->GetAtomCount(); ++i) {
+        if (classes->AtomAt(i) == nsNativeMenuAtoms::menuitem_with_favicon) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void
+nsMenuObject::ClearIcon() {
+    dbusmenu_menuitem_property_remove(mNativeData,
+                                      DBUSMENU_MENUITEM_PROP_ICON_DATA);
+}
+
+nsMenuObject::~nsMenuObject() {
+    nsWeakMenuObject::NotifyDestroyed(this);
+
+    if (mIconLoader) {
+        mIconLoader->Destroy();
+    }
+
+    if (mListener) {
+        mListener->UnregisterForContentChanges(mContent);
+    }
+
+    if (mNativeData) {
+        g_object_unref(mNativeData);
+        mNativeData = nullptr;
+    }
+}
+
+void
+nsMenuObject::CreateNativeData() {
+    MOZ_ASSERT(mNativeData == nullptr, "This node already has a DbusmenuMenuitem. The old one will be leaked");
+
+    mNativeData = dbusmenu_menuitem_new();
+    InitializeNativeData();
+    if (mParent && mParent->IsBeingDisplayed()) {
+        ContainerIsOpening();
+    }
+
+    mListener->RegisterForContentChanges(mContent, this);
+}
+
+nsresult
+nsMenuObject::AdoptNativeData(DbusmenuMenuitem* aNativeData) {
+    MOZ_ASSERT(mNativeData == nullptr, "This node already has a DbusmenuMenuitem. The old one will be leaked");
+
+    if (!IsCompatibleWithNativeData(aNativeData)) {
+        return NS_ERROR_FAILURE;
+    }
+
+    mNativeData = aNativeData;
+    g_object_ref(mNativeData);
+
+    PropertyFlags supported = SupportedProperties();
+    PropertyFlags mask = static_cast<PropertyFlags>(1);
+
+    for (uint32_t i = 0; gPropertyStrings[i]; ++i) {
+        if (!(mask & supported)) {
+            dbusmenu_menuitem_property_remove(mNativeData, gPropertyStrings[i]);
+        }
+        mask = static_cast<PropertyFlags>(mask << 1);
+    }
+
+    InitializeNativeData();
+    if (mParent && mParent->IsBeingDisplayed()) {
+        ContainerIsOpening();
+    }
+
+    mListener->RegisterForContentChanges(mContent, this);
+
+    return NS_OK;
+}
+
+void
+nsMenuObject::ContainerIsOpening() {
+    MOZ_ASSERT(nsContentUtils::IsSafeToRunScript());
+
+    UpdateContentAttributes();
+
+    RefPtr<nsStyleContext> sc = GetStyleContext();
+    Update(sc);
+}
+
+/* static */ void
+nsWeakMenuObject::AddWeakReference(nsWeakMenuObject* aWeak) {
+    aWeak->mPrev = sHead;
+    sHead = aWeak;
+}
+
+/* static */ void
+nsWeakMenuObject::RemoveWeakReference(nsWeakMenuObject* aWeak) {
+    if (aWeak == sHead) {
+        sHead = aWeak->mPrev;
+        return;
+    }
+
+    nsWeakMenuObject* weak = sHead;
+    while (weak && weak->mPrev != aWeak) {
+        weak = weak->mPrev;
+    }
+
+    if (weak) {
+        weak->mPrev = aWeak->mPrev;
+    }
+}
+
+/* static */ void
+nsWeakMenuObject::NotifyDestroyed(nsMenuObject* aMenuObject) {
+    nsWeakMenuObject* weak = sHead;
+    while (weak) {
+        if (weak->mMenuObject == aMenuObject) {
+            weak->mMenuObject = nullptr;
+        }
+
+        weak = weak->mPrev;
+    }
+}
diff --git a/widget/gtk/nsMenuObject.h b/widget/gtk/nsMenuObject.h
new file mode 100644
index 000000000..c7637cd05
--- /dev/null
+++ b/widget/gtk/nsMenuObject.h
@@ -0,0 +1,165 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenuObject_h__
+#define __nsMenuObject_h__
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+
+#include "nsDbusmenu.h"
+#include "nsNativeMenuDocListener.h"
+
+class nsIAtom;
+class nsIContent;
+class nsStyleContext;
+class nsMenuContainer;
+class nsMenuObjectIconLoader;
+
+#define DBUSMENU_PROPERTIES \
+    DBUSMENU_PROPERTY(Label, DBUSMENU_MENUITEM_PROP_LABEL, 0) \
+    DBUSMENU_PROPERTY(Enabled, DBUSMENU_MENUITEM_PROP_ENABLED, 1) \
+    DBUSMENU_PROPERTY(Visible, DBUSMENU_MENUITEM_PROP_VISIBLE, 2) \
+    DBUSMENU_PROPERTY(IconData, DBUSMENU_MENUITEM_PROP_ICON_DATA, 3) \
+    DBUSMENU_PROPERTY(Type, DBUSMENU_MENUITEM_PROP_TYPE, 4) \
+    DBUSMENU_PROPERTY(Shortcut, DBUSMENU_MENUITEM_PROP_SHORTCUT, 5) \
+    DBUSMENU_PROPERTY(ToggleType, DBUSMENU_MENUITEM_PROP_TOGGLE_TYPE, 6) \
+    DBUSMENU_PROPERTY(ToggleState, DBUSMENU_MENUITEM_PROP_TOGGLE_STATE, 7) \
+    DBUSMENU_PROPERTY(ChildDisplay, DBUSMENU_MENUITEM_PROP_CHILD_DISPLAY, 8)
+
+/*
+ * This is the base class for all menu nodes. Each instance represents
+ * a single node in the menu hierarchy. It wraps the corresponding DOM node and
+ * native menu node, keeps them in sync and transfers events between the two.
+ * It is not reference counted - each node is owned by its parent (the top
+ * level menubar is owned by the window) and keeps a weak pointer to its
+ * parent (which is guaranteed to always be valid because a node will never
+ * outlive its parent). It is not safe to keep a reference to nsMenuObject
+ * externally.
+ */
+class nsMenuObject : public nsNativeMenuChangeObserver {
+public:
+    enum EType {
+        eType_MenuBar,
+        eType_Menu,
+        eType_MenuItem
+    };
+
+    virtual ~nsMenuObject();
+
+    // Get the native menu item node
+    DbusmenuMenuitem* GetNativeData() const { return mNativeData; }
+
+    // Get the parent menu object
+    nsMenuContainer* Parent() const { return mParent; }
+
+    // Get the content node
+    nsIContent* ContentNode() const { return mContent; }
+
+    // Get the type of this node. Must be provided by subclasses
+    virtual EType Type() const = 0;
+
+    // Get the document listener
+    nsNativeMenuDocListener* DocListener() const { return mListener; }
+
+    // Create the native menu item node (called by containers)
+    void CreateNativeData();
+
+    // Adopt the specified native menu item node (called by containers)
+    nsresult AdoptNativeData(DbusmenuMenuitem* aNativeData);
+
+    // Called by the container to tell us that it's opening
+    void ContainerIsOpening();
+
+protected:
+    nsMenuObject(nsMenuContainer* aParent, nsIContent* aContent);
+    nsMenuObject(nsNativeMenuDocListener* aListener, nsIContent* aContent);
+
+    enum PropertyFlags {
+#define DBUSMENU_PROPERTY(e, s, b) eProp##e = (1 << b),
+        DBUSMENU_PROPERTIES
+#undef DBUSMENU_PROPERTY
+    };
+
+    void UpdateLabel();
+    void UpdateVisibility(nsStyleContext* aStyleContext);
+    void UpdateSensitivity();
+    void UpdateIcon(nsStyleContext* aStyleContext);
+
+    already_AddRefed<nsStyleContext> GetStyleContext();
+  
+private:
+    friend class nsMenuObjectIconLoader;
+
+    // Set up initial properties on the native data, connect to signals etc.
+    // This should be implemented by subclasses
+    virtual void InitializeNativeData();
+
+    // Return the properties that this menu object type supports
+    // This should be implemented by subclasses
+    virtual PropertyFlags SupportedProperties() const;
+
+    // Determine whether this menu object could use the specified
+    // native item. Returns true by default but can be overridden by subclasses
+    virtual bool
+    IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const;
+
+    // Update attributes on this objects content node when the container opens.
+    // This is called before style resolution, and should be implemented by
+    // subclasses who want to modify attributes that might affect style.
+    // This will not be called when there are script blockers
+    virtual void UpdateContentAttributes();
+
+    // Update properties that should be refreshed when the container opens.
+    // This should be implemented by subclasses that have properties which
+    // need refreshing
+    virtual void Update(nsStyleContext* aStyleContext);
+
+    bool ShouldShowIcon() const;
+    void ClearIcon();
+
+    nsCOMPtr<nsIContent> mContent;
+    // mListener is a strong ref for simplicity - someone in the tree needs to
+    // own it, and this only really needs to be the top-level object (as no
+    // children outlives their parent). However, we need to keep it alive until
+    // after running the nsMenuObject destructor for the top-level menu object,
+    // hence the strong ref
+    RefPtr<nsNativeMenuDocListener> mListener;
+    nsMenuContainer* mParent; // [weak]
+    DbusmenuMenuitem* mNativeData; // [strong]
+    RefPtr<nsMenuObjectIconLoader> mIconLoader;
+};
+
+// Keep a weak pointer to a menu object
+class nsWeakMenuObject {
+public:
+    nsWeakMenuObject() : mPrev(nullptr), mMenuObject(nullptr) {}
+
+    nsWeakMenuObject(nsMenuObject* aMenuObject) :
+        mPrev(nullptr), mMenuObject(aMenuObject)
+    {
+        AddWeakReference(this);
+    }
+
+    ~nsWeakMenuObject() { RemoveWeakReference(this); }
+
+    nsMenuObject* get() const { return mMenuObject; }
+
+    nsMenuObject* operator->() const { return mMenuObject; }
+
+    explicit operator bool() const { return !!mMenuObject; }
+
+    static void NotifyDestroyed(nsMenuObject* aMenuObject);
+
+private:
+    static void AddWeakReference(nsWeakMenuObject* aWeak);
+    static void RemoveWeakReference(nsWeakMenuObject* aWeak);
+
+    nsWeakMenuObject* mPrev;
+    static nsWeakMenuObject* sHead;
+
+    nsMenuObject* mMenuObject;
+};
+
+#endif /* __nsMenuObject_h__ */
diff --git a/widget/gtk/nsMenuSeparator.cpp b/widget/gtk/nsMenuSeparator.cpp
new file mode 100644
index 000000000..893c5c7f0
--- /dev/null
+++ b/widget/gtk/nsMenuSeparator.cpp
@@ -0,0 +1,74 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ *  file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Move.h"
+#include "nsAutoPtr.h"
+#include "nsCRT.h"
+#include "nsGkAtoms.h"
+#include "nsStyleContext.h"
+
+#include "nsDbusmenu.h"
+
+#include "nsMenuContainer.h"
+#include "nsMenuSeparator.h"
+
+using namespace mozilla;
+
+void
+nsMenuSeparator::InitializeNativeData() {
+    dbusmenu_menuitem_property_set(GetNativeData(),
+                                   DBUSMENU_MENUITEM_PROP_TYPE,
+                                   "separator");
+}
+
+void
+nsMenuSeparator::Update(nsStyleContext* aContext) {
+    UpdateVisibility(aContext);
+}
+
+bool
+nsMenuSeparator::IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const {
+    return nsCRT::strcmp(dbusmenu_menuitem_property_get(aNativeData,
+                                                        DBUSMENU_MENUITEM_PROP_TYPE),
+                         "separator") == 0;
+}
+
+nsMenuObject::PropertyFlags
+nsMenuSeparator::SupportedProperties() const {
+    return static_cast<nsMenuObject::PropertyFlags>(
+        nsMenuObject::ePropVisible |
+        nsMenuObject::ePropType
+    );
+}
+
+void
+nsMenuSeparator::OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) {
+    MOZ_ASSERT(aContent == ContentNode(), "Received an event that wasn't meant for us!");
+
+    if (!Parent()->IsBeingDisplayed()) {
+        return;
+    }
+
+    if (aAttribute == nsGkAtoms::hidden ||
+        aAttribute == nsGkAtoms::collapsed) {
+        RefPtr<nsStyleContext> sc = GetStyleContext();
+        UpdateVisibility(sc);
+    }
+}
+
+nsMenuSeparator::nsMenuSeparator(nsMenuContainer* aParent,
+                                 nsIContent* aContent) :
+    nsMenuObject(aParent, aContent) {
+    MOZ_COUNT_CTOR(nsMenuSeparator);
+}
+
+nsMenuSeparator::~nsMenuSeparator() {
+    MOZ_COUNT_DTOR(nsMenuSeparator);
+}
+
+nsMenuObject::EType
+nsMenuSeparator::Type() const {
+    return eType_MenuItem;
+}
diff --git a/widget/gtk/nsMenuSeparator.h b/widget/gtk/nsMenuSeparator.h
new file mode 100644
index 000000000..9ba770a85
--- /dev/null
+++ b/widget/gtk/nsMenuSeparator.h
@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsMenuSeparator_h__
+#define __nsMenuSeparator_h__
+
+#include "mozilla/Attributes.h"
+
+#include "nsMenuObject.h"
+
+class nsIContent;
+class nsIAtom;
+class nsMenuContainer;
+
+// Menu separator class
+class nsMenuSeparator final : public nsMenuObject {
+public:
+    nsMenuSeparator(nsMenuContainer* aParent, nsIContent* aContent);
+    ~nsMenuSeparator();
+
+    nsMenuObject::EType Type() const override;
+
+private:
+    void InitializeNativeData() override;
+    void Update(nsStyleContext* aStyleContext) override;
+    bool IsCompatibleWithNativeData(DbusmenuMenuitem* aNativeData) const override;
+    nsMenuObject::PropertyFlags SupportedProperties() const override;
+
+    void OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) override;
+};
+
+#endif /* __nsMenuSeparator_h__ */
diff --git a/widget/gtk/nsNativeMenuAtomList.h b/widget/gtk/nsNativeMenuAtomList.h
new file mode 100644
index 000000000..4a8b3869a
--- /dev/null
+++ b/widget/gtk/nsNativeMenuAtomList.h
@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+WIDGET_ATOM2(menuitem_with_favicon, "menuitem-with-favicon")
+WIDGET_ATOM2(_moz_menubarkeeplocal, "_moz-menubarkeeplocal")
+WIDGET_ATOM2(_moz_nativemenupopupstate, "_moz-nativemenupopupstate")
+WIDGET_ATOM(openedwithkey)
+WIDGET_ATOM(shellshowingmenubar)
diff --git a/widget/gtk/nsNativeMenuAtoms.cpp b/widget/gtk/nsNativeMenuAtoms.cpp
new file mode 100644
index 000000000..f43d8b24b
--- /dev/null
+++ b/widget/gtk/nsNativeMenuAtoms.cpp
@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIAtom.h"
+#include "nsStaticAtom.h"
+
+#include "nsNativeMenuAtoms.h"
+
+using namespace mozilla;
+
+#define WIDGET_ATOM(_name) nsIAtom* nsNativeMenuAtoms::_name;
+#define WIDGET_ATOM2(_name, _value) nsIAtom* nsNativeMenuAtoms::_name;
+#include "nsNativeMenuAtomList.h"
+#undef WIDGET_ATOM
+#undef WIDGET_ATOM2
+
+#define WIDGET_ATOM(name_) NS_STATIC_ATOM_BUFFER(name_##_buffer, #name_)
+#define WIDGET_ATOM2(name_, value_) NS_STATIC_ATOM_BUFFER(name_##_buffer, value_)
+#include "nsNativeMenuAtomList.h"
+#undef WIDGET_ATOM
+#undef WIDGET_ATOM2
+
+static const nsStaticAtom gAtoms[] = {
+#define WIDGET_ATOM(name_) NS_STATIC_ATOM(name_##_buffer, &nsNativeMenuAtoms::name_),
+#define WIDGET_ATOM2(name_, value_) NS_STATIC_ATOM(name_##_buffer, &nsNativeMenuAtoms::name_),
+#include "nsNativeMenuAtomList.h"
+#undef WIDGET_ATOM
+#undef WIDGET_ATOM2
+};
+
+/* static */ void
+nsNativeMenuAtoms::RegisterAtoms() {
+    NS_RegisterStaticAtoms(gAtoms);
+}
diff --git a/widget/gtk/nsNativeMenuAtoms.h b/widget/gtk/nsNativeMenuAtoms.h
new file mode 100644
index 000000000..4a9766ee8
--- /dev/null
+++ b/widget/gtk/nsNativeMenuAtoms.h
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsNativeMenuAtoms_h__
+#define __nsNativeMenuAtoms_h__
+
+class nsIAtom;
+
+class nsNativeMenuAtoms {
+public:
+    nsNativeMenuAtoms() = delete;
+
+    static void RegisterAtoms();
+
+#define WIDGET_ATOM(_name) static nsIAtom* _name;
+#define WIDGET_ATOM2(_name, _value) static nsIAtom* _name;
+#include "nsNativeMenuAtomList.h"
+#undef WIDGET_ATOM
+#undef WIDGET_ATOM2
+};
+
+#endif /* __nsNativeMenuAtoms_h__ */
diff --git a/widget/gtk/nsNativeMenuDocListener.cpp b/widget/gtk/nsNativeMenuDocListener.cpp
new file mode 100644
index 000000000..46a9c3aa9
--- /dev/null
+++ b/widget/gtk/nsNativeMenuDocListener.cpp
@@ -0,0 +1,329 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/dom/Element.h"
+#include "nsContentUtils.h"
+#include "nsIAtom.h"
+#include "nsIContent.h"
+#include "nsIDocument.h"
+
+#include "nsMenuContainer.h"
+
+#include "nsNativeMenuDocListener.h"
+
+using namespace mozilla;
+
+uint32_t nsNativeMenuDocListener::sUpdateBlockersCount = 0;
+
+nsNativeMenuDocListenerTArray* gPendingListeners;
+
+/*
+ * Small helper which caches a single listener, so that consecutive
+ * events which go to the same node avoid multiple hash table lookups
+ */
+class MOZ_STACK_CLASS DispatchHelper {
+public:
+    DispatchHelper(nsNativeMenuDocListener* aListener,
+                   nsIContent* aContent
+                   MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+                   mObserver(nullptr) {
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+        if (aContent == aListener->mLastSource) {
+            mObserver = aListener->mLastTarget;
+        } else {
+            mObserver = aListener->mContentToObserverTable.Get(aContent);
+            if (mObserver) {
+                aListener->mLastSource = aContent;
+                aListener->mLastTarget = mObserver;
+            }
+        }
+    }
+
+    ~DispatchHelper() { };
+
+    nsNativeMenuChangeObserver* Observer() const {
+      return mObserver; 
+    }
+
+    bool HasObserver() const {
+      return !!mObserver;
+    }
+
+private:
+    nsNativeMenuChangeObserver* mObserver;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+NS_IMPL_ISUPPORTS(nsNativeMenuDocListener, nsIMutationObserver)
+
+nsNativeMenuDocListener::~nsNativeMenuDocListener() {
+    MOZ_ASSERT(mContentToObserverTable.Count() == 0,
+               "Some nodes forgot to unregister listeners. This is bad! (and we're lucky we made it this far)");
+    MOZ_COUNT_DTOR(nsNativeMenuDocListener);
+}
+
+void
+nsNativeMenuDocListener::AttributeChanged(nsIDocument* aDocument,
+                                          mozilla::dom::Element* aElement,
+                                          int32_t aNameSpaceID,
+                                          nsIAtom* aAttribute,
+                                          int32_t aModType,
+                                          const nsAttrValue* aOldValue) {
+    if (sUpdateBlockersCount == 0) {
+        DoAttributeChanged(aElement, aAttribute);
+        return;
+    }
+
+    MutationRecord* m =* mPendingMutations.AppendElement(new MutationRecord);
+    m->mType = MutationRecord::eAttributeChanged;
+    m->mTarget = aElement;
+    m->mAttribute = aAttribute;
+
+    ScheduleFlush(this);
+}
+
+void
+nsNativeMenuDocListener::ContentAppended(nsIDocument* aDocument,
+                                         nsIContent* aContainer,
+                                         nsIContent* aFirstNewContent,
+                                         int32_t aNewIndexInContainer) {
+    for (nsIContent* c = aFirstNewContent; c; c = c->GetNextSibling()) {
+        ContentInserted(aDocument, aContainer, c, 0);
+    }
+}
+
+void
+nsNativeMenuDocListener::ContentInserted(nsIDocument* aDocument,
+                                         nsIContent* aContainer,
+                                         nsIContent* aChild,
+                                         int32_t aIndexInContainer) {
+    nsIContent* prevSibling = nsMenuContainer::GetPreviousSupportedSibling(aChild);
+
+    if (sUpdateBlockersCount == 0) {
+        DoContentInserted(aContainer, aChild, prevSibling);
+        return;
+    }
+
+    MutationRecord* m =* mPendingMutations.AppendElement(new MutationRecord);
+    m->mType = MutationRecord::eContentInserted;
+    m->mTarget = aContainer;
+    m->mChild = aChild;
+    m->mPrevSibling = prevSibling;
+
+    ScheduleFlush(this);
+}
+
+void
+nsNativeMenuDocListener::ContentRemoved(nsIDocument* aDocument,
+                                        nsIContent* aContainer,
+                                        nsIContent* aChild,
+                                        int32_t aIndexInContainer,
+                                        nsIContent* aPreviousSibling) {
+    if (sUpdateBlockersCount == 0) {
+        DoContentRemoved(aContainer, aChild);
+        return;
+    }
+
+    MutationRecord* m =* mPendingMutations.AppendElement(new MutationRecord);
+    m->mType = MutationRecord::eContentRemoved;
+    m->mTarget = aContainer;
+    m->mChild = aChild;
+
+    ScheduleFlush(this);
+}                                                           
+
+void
+nsNativeMenuDocListener::NodeWillBeDestroyed(const nsINode* aNode) {
+    mDocument = nullptr;
+}
+
+void
+nsNativeMenuDocListener::DoAttributeChanged(nsIContent* aContent,
+                                            nsIAtom* aAttribute) {
+    DispatchHelper h(this, aContent);
+    if (h.HasObserver()) {
+        h.Observer()->OnAttributeChanged(aContent, aAttribute);
+    }
+}
+
+void
+nsNativeMenuDocListener::DoContentInserted(nsIContent* aContainer,
+                                           nsIContent* aChild,
+                                           nsIContent* aPrevSibling) {
+    DispatchHelper h(this, aContainer);
+    if (h.HasObserver()) {
+        h.Observer()->OnContentInserted(aContainer, aChild, aPrevSibling);
+    }
+}
+
+void
+nsNativeMenuDocListener::DoContentRemoved(nsIContent* aContainer,
+                                          nsIContent* aChild) {
+    DispatchHelper h(this, aContainer);
+    if (h.HasObserver()) {
+        h.Observer()->OnContentRemoved(aContainer, aChild);
+    }
+}
+
+void
+nsNativeMenuDocListener::DoBeginUpdates(nsIContent* aTarget) {
+    DispatchHelper h(this, aTarget);
+    if (h.HasObserver()) {
+        h.Observer()->OnBeginUpdates(aTarget);
+    }
+}
+
+void
+nsNativeMenuDocListener::DoEndUpdates(nsIContent* aTarget) {
+    DispatchHelper h(this, aTarget);
+    if (h.HasObserver()) {
+        h.Observer()->OnEndUpdates();
+    }
+}
+
+void
+nsNativeMenuDocListener::FlushPendingMutations() {
+    nsIContent* currentTarget = nullptr;
+    bool inUpdateSequence = false;
+
+    while (mPendingMutations.Length() > 0) {
+        MutationRecord* m = mPendingMutations[0];
+
+        if (m->mTarget != currentTarget) {
+            if (inUpdateSequence) {
+                DoEndUpdates(currentTarget);
+                inUpdateSequence = false;
+            }
+
+            currentTarget = m->mTarget;
+
+            if (mPendingMutations.Length() > 1 &&
+                mPendingMutations[1]->mTarget == currentTarget) {
+                DoBeginUpdates(currentTarget);
+                inUpdateSequence = true;
+            }
+        }
+
+        switch (m->mType) {
+            case MutationRecord::eAttributeChanged:
+                DoAttributeChanged(m->mTarget, m->mAttribute);
+                break;
+            case MutationRecord::eContentInserted:
+                DoContentInserted(m->mTarget, m->mChild, m->mPrevSibling);
+                break;
+            case MutationRecord::eContentRemoved:
+                DoContentRemoved(m->mTarget, m->mChild);
+                break;
+            default:
+                NS_NOTREACHED("Invalid type");
+        }
+
+        mPendingMutations.RemoveElementAt(0);
+    }
+
+    if (inUpdateSequence) {
+        DoEndUpdates(currentTarget);
+    }
+}
+
+/* static */ void
+nsNativeMenuDocListener::ScheduleFlush(nsNativeMenuDocListener* aListener) {
+    MOZ_ASSERT(sUpdateBlockersCount > 0, "Shouldn't be doing this now");
+
+    if (!gPendingListeners) {
+        gPendingListeners = new nsNativeMenuDocListenerTArray;
+    }
+
+    if (gPendingListeners->IndexOf(aListener) ==
+        nsNativeMenuDocListenerTArray::NoIndex) {
+        gPendingListeners->AppendElement(aListener);
+    }
+}
+
+/* static */ void
+nsNativeMenuDocListener::CancelFlush(nsNativeMenuDocListener* aListener) {
+    if (!gPendingListeners) {
+        return;
+    }
+
+    gPendingListeners->RemoveElement(aListener);
+}
+
+/* static */ void
+nsNativeMenuDocListener::RemoveUpdateBlocker() {
+    if (sUpdateBlockersCount == 1 && gPendingListeners) {
+        while (gPendingListeners->Length() > 0) {
+            (*gPendingListeners)[0]->FlushPendingMutations();
+            gPendingListeners->RemoveElementAt(0);
+        }
+    }
+ 
+    MOZ_ASSERT(sUpdateBlockersCount > 0, "Negative update blockers count!");
+    sUpdateBlockersCount--;
+}
+
+nsNativeMenuDocListener::nsNativeMenuDocListener(nsIContent* aRootNode) :
+    mRootNode(aRootNode),
+    mDocument(nullptr),
+    mLastSource(nullptr),
+    mLastTarget(nullptr) {
+    MOZ_COUNT_CTOR(nsNativeMenuDocListener);
+}
+
+void
+nsNativeMenuDocListener::RegisterForContentChanges(nsIContent* aContent,
+                                                   nsNativeMenuChangeObserver* aObserver) {
+    MOZ_ASSERT(aContent, "Need content parameter");
+    MOZ_ASSERT(aObserver, "Need observer parameter");
+    if (!aContent || !aObserver) {
+        return;
+    }
+
+    DebugOnly<nsNativeMenuChangeObserver* > old;
+    MOZ_ASSERT(!mContentToObserverTable.Get(aContent, &old) || old == aObserver,
+               "Multiple observers for the same content node are not supported");
+
+    mContentToObserverTable.Put(aContent, aObserver);
+}
+
+void
+nsNativeMenuDocListener::UnregisterForContentChanges(nsIContent* aContent) {
+    MOZ_ASSERT(aContent, "Need content parameter");
+    if (!aContent) {
+        return;
+    }
+
+    mContentToObserverTable.Remove(aContent);
+    if (aContent == mLastSource) {
+        mLastSource = nullptr;
+        mLastTarget = nullptr;
+    }
+}
+
+void
+nsNativeMenuDocListener::Start() {
+    if (mDocument) {
+        return;
+    }
+
+    mDocument = mRootNode->OwnerDoc();
+    if (!mDocument) {
+        return;
+    }
+
+    mDocument->AddMutationObserver(this);
+}
+
+void
+nsNativeMenuDocListener::Stop() {
+    if (mDocument) {
+        mDocument->RemoveMutationObserver(this);
+        mDocument = nullptr;
+    }
+
+    CancelFlush(this);
+    mPendingMutations.Clear();
+}
diff --git a/widget/gtk/nsNativeMenuDocListener.h b/widget/gtk/nsNativeMenuDocListener.h
new file mode 100644
index 000000000..c0a503da1
--- /dev/null
+++ b/widget/gtk/nsNativeMenuDocListener.h
@@ -0,0 +1,146 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsNativeMenuDocListener_h__
+#define __nsNativeMenuDocListener_h__
+
+#include "mozilla/Attributes.h"
+#include "mozilla/GuardObjects.h"
+#include "mozilla/RefPtr.h"
+#include "nsAutoPtr.h"
+#include "nsDataHashtable.h"
+#include "nsStubMutationObserver.h"
+#include "nsTArray.h"
+
+class nsIAtom;
+class nsIContent;
+class nsIDocument;
+class nsNativeMenuChangeObserver;
+
+/*
+ * This class keeps a mapping of content nodes to observers and forwards DOM
+ * mutations to these. There is exactly one of these for every menubar.
+ */
+class nsNativeMenuDocListener final : nsStubMutationObserver {
+public:
+    NS_DECL_ISUPPORTS
+
+    nsNativeMenuDocListener(nsIContent* aRootNode);
+
+    // Register an observer to receive mutation events for the specified
+    // content node. The caller must keep the observer alive until
+    // UnregisterForContentChanges is called.
+    void RegisterForContentChanges(nsIContent* aContent,
+                                   nsNativeMenuChangeObserver* aObserver);
+
+    // Unregister the registered observer for the specified content node
+    void UnregisterForContentChanges(nsIContent* aContent);
+
+    // Start listening to the document and forwarding DOM mutations to
+    // registered observers.
+    void Start();
+
+    // Stop listening to the document. No DOM mutations will be forwarded
+    // to registered observers.
+    void Stop();
+
+    /*
+     * This class is intended to be used inside GObject signal handlers.
+     * It allows us to queue updates until we have finished delivering
+     * events to Goanna, and then we can batch updates to our view of the
+     * menu. This allows us to do menu updates without altering the structure
+     * seen by the OS.
+     */
+    class MOZ_STACK_CLASS BlockUpdatesScope {
+    public:
+        BlockUpdatesScope(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM) {
+            MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+            nsNativeMenuDocListener::AddUpdateBlocker();
+        }
+
+        ~BlockUpdatesScope() {
+            nsNativeMenuDocListener::RemoveUpdateBlocker();
+        }
+
+    private:
+        MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+    };
+
+private:
+    friend class DispatchHelper;
+
+    struct MutationRecord {
+        enum RecordType {
+            eAttributeChanged,
+            eContentInserted,
+            eContentRemoved
+        } mType;
+
+        nsCOMPtr<nsIContent> mTarget;
+        nsCOMPtr<nsIContent> mChild;
+        nsCOMPtr<nsIContent> mPrevSibling;
+        nsCOMPtr<nsIAtom> mAttribute;
+    };
+
+    ~nsNativeMenuDocListener();
+
+    NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
+    NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED
+    NS_DECL_NSIMUTATIONOBSERVER_NODEWILLBEDESTROYED
+
+    void DoAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute);
+    void DoContentInserted(nsIContent* aContainer,
+                           nsIContent* aChild,
+                           nsIContent* aPrevSibling);
+    void DoContentRemoved(nsIContent* aContainer, nsIContent* aChild);
+    void DoBeginUpdates(nsIContent* aTarget);
+    void DoEndUpdates(nsIContent* aTarget);
+
+    void FlushPendingMutations();
+    static void ScheduleFlush(nsNativeMenuDocListener* aListener);
+    static void CancelFlush(nsNativeMenuDocListener* aListener);
+
+    static void AddUpdateBlocker() {
+      ++sUpdateBlockersCount;
+    }
+    static void RemoveUpdateBlocker();
+
+    nsCOMPtr<nsIContent> mRootNode;
+    nsIDocument* mDocument;
+    nsIContent* mLastSource;
+    nsNativeMenuChangeObserver* mLastTarget;
+    nsTArray<nsAutoPtr<MutationRecord> > mPendingMutations;
+    nsDataHashtable<nsPtrHashKey<nsIContent>, nsNativeMenuChangeObserver* > mContentToObserverTable;
+
+    static uint32_t sUpdateBlockersCount;
+};
+
+typedef nsTArray<RefPtr<nsNativeMenuDocListener> > nsNativeMenuDocListenerTArray;
+
+/*
+ *  Implemented by classes that want to listen to mutation events from content
+ *  nodes.
+ */
+class nsNativeMenuChangeObserver {
+public:
+    virtual void OnAttributeChanged(nsIContent* aContent, nsIAtom* aAttribute) {}
+
+    virtual void OnContentInserted(nsIContent* aContainer,
+                                   nsIContent* aChild,
+                                   nsIContent* aPrevSibling) {}
+
+    virtual void OnContentRemoved(nsIContent* aContainer, nsIContent* aChild) {}
+
+    // Signals the start of a sequence of more than 1 event for the specified
+    // node. This only happens when events are flushed as all BlockUpdatesScope
+    // instances go out of scope
+    virtual void OnBeginUpdates(nsIContent* aContent) {};
+
+    // Signals the end of a sequence of events
+    virtual void OnEndUpdates() {};
+};
+
+#endif /* __nsNativeMenuDocListener_h__ */
diff --git a/widget/gtk/nsNativeMenuService.cpp b/widget/gtk/nsNativeMenuService.cpp
new file mode 100644
index 000000000..eabe77ca8
--- /dev/null
+++ b/widget/gtk/nsNativeMenuService.cpp
@@ -0,0 +1,485 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Move.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/UniquePtr.h"
+#include "nsAutoPtr.h"
+#include "nsCOMPtr.h"
+#include "nsCRT.h"
+#include "nsGtkUtils.h"
+#include "nsIContent.h"
+#include "nsIWidget.h"
+#include "nsServiceManagerUtils.h"
+#include "nsWindow.h"
+#include "prlink.h"
+
+#include "nsDbusmenu.h"
+#include "nsMenuBar.h"
+#include "nsNativeMenuAtoms.h"
+#include "nsNativeMenuDocListener.h"
+
+#include <glib-object.h>
+#include <pango/pango.h>
+#include <stdlib.h>
+
+#include "nsNativeMenuService.h"
+
+using namespace mozilla;
+
+nsNativeMenuService* nsNativeMenuService::sService = nullptr;
+
+extern PangoLayout* gPangoLayout;
+extern nsNativeMenuDocListenerTArray* gPendingListeners;
+
+static const nsTArray<nsMenuBar* >::index_type NoIndex = nsTArray<nsMenuBar* >::NoIndex;
+
+#if not GLIB_CHECK_VERSION(2,26,0)
+enum GBusType {
+    G_BUS_TYPE_STARTER = -1,
+    G_BUS_TYPE_NONE = 0,
+    G_BUS_TYPE_SYSTEM = 1,
+    G_BUS_TYPE_SESSION = 2
+};
+
+enum GDBusProxyFlags {
+    G_DBUS_PROXY_FLAGS_NONE = 0,
+    G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES = 1 << 0,
+    G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS = 1 << 1,
+    G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START = 1 << 2,
+    G_DBUS_PROXY_FLAGS_GET_INVALIDATED_PROPERTIES = 1 << 3
+};
+
+enum GDBusCallFlags {
+    G_DBUS_CALL_FLAGS_NONE = 0,
+    G_DBUS_CALL_FLAGS_NO_AUTO_START = 1 << 0
+};
+
+typedef _GDBusInterfaceInfo GDBusInterfaceInfo;
+typedef _GDBusProxy GDBusProxy;
+typedef _GVariant GVariant;
+#endif
+
+#undef g_dbus_proxy_new_for_bus
+#undef g_dbus_proxy_new_for_bus_finish
+#undef g_dbus_proxy_call
+#undef g_dbus_proxy_call_finish
+#undef g_dbus_proxy_get_name_owner
+
+typedef void (*_g_dbus_proxy_new_for_bus_fn)(GBusType, GDBusProxyFlags,
+                                             GDBusInterfaceInfo*,
+                                             const gchar*, const gchar*,
+                                             const gchar*, GCancellable*,
+                                             GAsyncReadyCallback, gpointer);
+
+typedef GDBusProxy* (*_g_dbus_proxy_new_for_bus_finish_fn)(GAsyncResult*,
+                                                           GError**);
+typedef void (*_g_dbus_proxy_call_fn)(GDBusProxy*, const gchar*, GVariant*,
+                                      GDBusCallFlags, gint, GCancellable*,
+                                      GAsyncReadyCallback, gpointer);
+typedef GVariant* (*_g_dbus_proxy_call_finish_fn)(GDBusProxy*, GAsyncResult*,
+                                                  GError**);
+typedef gchar* (*_g_dbus_proxy_get_name_owner_fn)(GDBusProxy*);
+
+static _g_dbus_proxy_new_for_bus_fn _g_dbus_proxy_new_for_bus;
+static _g_dbus_proxy_new_for_bus_finish_fn _g_dbus_proxy_new_for_bus_finish;
+static _g_dbus_proxy_call_fn _g_dbus_proxy_call;
+static _g_dbus_proxy_call_finish_fn _g_dbus_proxy_call_finish;
+static _g_dbus_proxy_get_name_owner_fn _g_dbus_proxy_get_name_owner;
+
+#define g_dbus_proxy_new_for_bus _g_dbus_proxy_new_for_bus
+#define g_dbus_proxy_new_for_bus_finish _g_dbus_proxy_new_for_bus_finish
+#define g_dbus_proxy_call _g_dbus_proxy_call
+#define g_dbus_proxy_call_finish _g_dbus_proxy_call_finish
+#define g_dbus_proxy_get_name_owner _g_dbus_proxy_get_name_owner
+
+static PRLibrary* gGIOLib = nullptr;
+
+static nsresult
+GDBusInit() {
+    gGIOLib = PR_LoadLibrary("libgio-2.0.so.0");
+    if (!gGIOLib) {
+        return NS_ERROR_FAILURE;
+    }
+
+    g_dbus_proxy_new_for_bus = (_g_dbus_proxy_new_for_bus_fn)PR_FindFunctionSymbol(gGIOLib, "g_dbus_proxy_new_for_bus");
+    g_dbus_proxy_new_for_bus_finish = (_g_dbus_proxy_new_for_bus_finish_fn)PR_FindFunctionSymbol(gGIOLib, "g_dbus_proxy_new_for_bus_finish");
+    g_dbus_proxy_call = (_g_dbus_proxy_call_fn)PR_FindFunctionSymbol(gGIOLib, "g_dbus_proxy_call");
+    g_dbus_proxy_call_finish = (_g_dbus_proxy_call_finish_fn)PR_FindFunctionSymbol(gGIOLib, "g_dbus_proxy_call_finish");
+    g_dbus_proxy_get_name_owner = (_g_dbus_proxy_get_name_owner_fn)PR_FindFunctionSymbol(gGIOLib, "g_dbus_proxy_get_name_owner");
+
+    if (!g_dbus_proxy_new_for_bus ||
+        !g_dbus_proxy_new_for_bus_finish ||
+        !g_dbus_proxy_call ||
+        !g_dbus_proxy_call_finish ||
+        !g_dbus_proxy_get_name_owner) {
+        return NS_ERROR_FAILURE;
+    }
+
+    return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(nsNativeMenuService, nsINativeMenuService)
+
+nsNativeMenuService::nsNativeMenuService() :
+    mCreateProxyCancellable(nullptr), mDbusProxy(nullptr), mOnline(false) {
+}
+
+nsNativeMenuService::~nsNativeMenuService() {
+    SetOnline(false);
+
+    if (mCreateProxyCancellable) {
+        g_cancellable_cancel(mCreateProxyCancellable);
+        g_object_unref(mCreateProxyCancellable);
+        mCreateProxyCancellable = nullptr;
+    }
+
+    // Make sure we disconnect map-event handlers
+    while (mMenuBars.Length() > 0) {
+        NotifyNativeMenuBarDestroyed(mMenuBars[0]);
+    }
+
+    Preferences::UnregisterCallback(PrefChangedCallback,
+                                    "ui.use_global_menubar");
+
+    if (mDbusProxy) {
+        g_signal_handlers_disconnect_by_func(mDbusProxy,
+                                             FuncToGpointer(name_owner_changed_cb),
+                                             NULL);
+        g_object_unref(mDbusProxy);
+    }
+
+    if (gPendingListeners) {
+        delete gPendingListeners;
+        gPendingListeners = nullptr;
+    }
+    if (gPangoLayout) {
+        g_object_unref(gPangoLayout);
+        gPangoLayout = nullptr;
+    }
+
+    MOZ_ASSERT(sService == this);
+    sService = nullptr;
+}
+
+nsresult
+nsNativeMenuService::Init() {
+    nsresult rv = nsDbusmenuFunctions::Init();
+    if (NS_FAILED(rv)) {
+        return rv;
+    }
+
+    rv = GDBusInit();
+    if (NS_FAILED(rv)) {
+        return rv;
+    }
+
+    Preferences::RegisterCallback(PrefChangedCallback,
+                                  "ui.use_global_menubar");
+
+    mCreateProxyCancellable = g_cancellable_new();
+
+    g_dbus_proxy_new_for_bus(G_BUS_TYPE_SESSION,
+                             static_cast<GDBusProxyFlags>(
+                                 G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
+                                 G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS |
+                                 G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START),
+                             nullptr,
+                             "com.canonical.AppMenu.Registrar",
+                             "/com/canonical/AppMenu/Registrar",
+                             "com.canonical.AppMenu.Registrar",
+                             mCreateProxyCancellable, proxy_created_cb,
+                             nullptr);
+
+    /* We don't technically know that the shell will draw the menubar until
+     * we know whether anybody owns the name of the menubar service on the
+     * session bus. However, discovering this happens asynchronously so
+     * we optimize for the common case here by assuming that the shell will
+     * draw window menubars if we are running inside Unity. This should
+     * mean that we avoid temporarily displaying the window menubar ourselves
+     */
+    const char* desktop = getenv("XDG_CURRENT_DESKTOP");
+    if (nsCRT::strcmp(desktop, "Unity") == 0) {
+        SetOnline(true);
+    }
+
+    return NS_OK;
+}
+
+/* static */ void
+nsNativeMenuService::EnsureInitialized() {
+    if (sService) {
+        return;
+    }
+    nsCOMPtr<nsINativeMenuService> service =
+        do_GetService("@mozilla.org/widget/nativemenuservice;1");
+}
+
+void
+nsNativeMenuService::SetOnline(bool aOnline) {
+    if (!Preferences::GetBool("ui.use_global_menubar", true)) {
+        aOnline = false;
+    }
+
+    mOnline = aOnline;
+    if (aOnline) {
+        for (uint32_t i = 0; i < mMenuBars.Length(); ++i) {
+            RegisterNativeMenuBar(mMenuBars[i]);
+        }
+    } else {
+        for (uint32_t i = 0; i < mMenuBars.Length(); ++i) {
+            mMenuBars[i]->Deactivate();
+        }
+    }
+}
+
+void
+nsNativeMenuService::RegisterNativeMenuBar(nsMenuBar* aMenuBar) {
+    if (!mOnline) {
+        return;
+    }
+
+    // This will effectively create the native menubar for
+    // exporting over the session bus, and hide the XUL menubar
+    aMenuBar->Activate();
+
+    if (!mDbusProxy ||
+        !gtk_widget_get_mapped(aMenuBar->TopLevelWindow()) ||
+        mMenuBarRegistrationCancellables.Get(aMenuBar, nullptr)) {
+        // Don't go further if we don't have a proxy for the shell menu
+        // service, the window isn't mapped or there is a request in progress.
+        return;
+    }
+
+    uint32_t xid = aMenuBar->WindowId();
+    nsAdoptingCString path = aMenuBar->ObjectPath();
+    if (xid == 0 || path.IsEmpty()) {
+        NS_WARNING("Menubar has invalid XID or object path");
+        return;
+    }
+
+    GCancellable* cancellable = g_cancellable_new();
+    mMenuBarRegistrationCancellables.Put(aMenuBar, cancellable);
+
+    // We keep a weak ref because we can't assume that GDBus cancellation
+    // is reliable (see https://launchpad.net/bugs/953562)
+
+    g_dbus_proxy_call(mDbusProxy, "RegisterWindow",
+                      g_variant_new("(uo)", xid, path.get()),
+                      G_DBUS_CALL_FLAGS_NONE, -1,
+                      cancellable,
+                      register_native_menubar_cb, aMenuBar);
+}
+
+/* static */ void
+nsNativeMenuService::name_owner_changed_cb(GObject* gobject,
+                                           GParamSpec* pspec,
+                                           gpointer user_data) {
+    nsNativeMenuService::GetSingleton()->OnNameOwnerChanged();
+}
+
+/* static */ void
+nsNativeMenuService::proxy_created_cb(GObject* source_object,
+                                      GAsyncResult* res,
+                                      gpointer user_data) {
+    GError* error = nullptr;
+    GDBusProxy* proxy = g_dbus_proxy_new_for_bus_finish(res, &error);
+    if (error && g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED)) {
+        g_error_free(error);
+        return;
+    }
+
+    if (error) {
+        g_error_free(error);
+    }
+
+    // We need this check because we can't assume that GDBus cancellation
+    // is reliable (see https://launchpad.net/bugs/953562)
+    nsNativeMenuService* self = nsNativeMenuService::GetSingleton();
+    if (!self) {
+        if (proxy) {
+            g_object_unref(proxy);
+        }
+        return;
+    }
+
+    self->OnProxyCreated(proxy);
+}
+
+/* static */ void
+nsNativeMenuService::register_native_menubar_cb(GObject* source_object,
+                                                GAsyncResult* res,
+                                                gpointer user_data) {
+    nsMenuBar* menuBar = static_cast<nsMenuBar* >(user_data);
+
+    GError* error = nullptr;
+    GVariant* results = g_dbus_proxy_call_finish(G_DBUS_PROXY(source_object),
+                                                 res, &error);
+    if (results) {
+        // There's nothing useful in the response
+        g_variant_unref(results);
+    }
+
+    bool success = error ? false : true;
+    if (error && g_error_matches(error, G_IO_ERROR, G_IO_ERROR_CANCELLED)) {
+        g_error_free(error);
+        return;
+    }
+
+    if (error) {
+        g_error_free(error);
+    }
+
+    nsNativeMenuService* self = nsNativeMenuService::GetSingleton();
+    if (!self) {
+        return;
+    }
+
+    self->OnNativeMenuBarRegistered(menuBar, success);
+}
+
+/* static */ gboolean
+nsNativeMenuService::map_event_cb(GtkWidget* widget,
+                                  GdkEvent* event,
+                                  gpointer user_data) {
+    nsMenuBar* menubar = static_cast<nsMenuBar* >(user_data);
+    nsNativeMenuService::GetSingleton()->RegisterNativeMenuBar(menubar);
+
+    return FALSE;
+}
+
+void
+nsNativeMenuService::OnNameOwnerChanged() {
+    char* owner = g_dbus_proxy_get_name_owner(mDbusProxy);
+    SetOnline(owner ? true : false);
+    g_free(owner);
+}
+
+void
+nsNativeMenuService::OnProxyCreated(GDBusProxy* aProxy) {
+    mDbusProxy = aProxy;
+
+    g_object_unref(mCreateProxyCancellable);
+    mCreateProxyCancellable = nullptr;
+
+    if (!mDbusProxy) {
+        SetOnline(false);
+        return;
+    }
+
+    g_signal_connect(mDbusProxy, "notify::g-name-owner",
+                     G_CALLBACK(name_owner_changed_cb), nullptr);
+
+    OnNameOwnerChanged();
+}
+
+void
+nsNativeMenuService::OnNativeMenuBarRegistered(nsMenuBar* aMenuBar,
+                                               bool aSuccess) {
+    // Don't assume that GDBus cancellation is reliable (ie, |aMenuBar| might
+    // have already been deleted (see https://launchpad.net/bugs/953562)
+    GCancellable* cancellable = nullptr;
+    if (!mMenuBarRegistrationCancellables.Get(aMenuBar, &cancellable)) {
+        return;
+    }
+
+    g_object_unref(cancellable);
+    mMenuBarRegistrationCancellables.Remove(aMenuBar);
+
+    if (!aSuccess) {
+        aMenuBar->Deactivate();
+    }
+}
+
+/* static */ void
+nsNativeMenuService::PrefChangedCallback(const char* aPref,
+                                         void* aClosure) {
+    nsNativeMenuService::GetSingleton()->PrefChanged();
+}
+
+void
+nsNativeMenuService::PrefChanged() {
+    if (!mDbusProxy) {
+        SetOnline(false);
+        return;
+    }
+
+    OnNameOwnerChanged();
+}
+
+NS_IMETHODIMP
+nsNativeMenuService::CreateNativeMenuBar(nsIWidget* aParent,
+                                         nsIContent* aMenuBarNode) {
+    NS_ENSURE_ARG(aParent);
+    NS_ENSURE_ARG(aMenuBarNode);
+
+    if (aMenuBarNode->AttrValueIs(kNameSpaceID_None,
+                                  nsNativeMenuAtoms::_moz_menubarkeeplocal,
+                                  nsGkAtoms::_true,
+                                  eCaseMatters)) {
+        return NS_OK;
+    }
+
+    UniquePtr<nsMenuBar> menubar(nsMenuBar::Create(aParent, aMenuBarNode));
+    if (!menubar) {
+        NS_WARNING("Failed to create menubar");
+        return NS_ERROR_FAILURE;
+    }
+
+    // Unity forgets our window if it is unmapped by the application, which
+    // happens with some extensions that add "minimize to tray" type
+    // functionality. We hook on to the MapNotify event to re-register our menu
+    // with Unity
+    g_signal_connect(G_OBJECT(menubar->TopLevelWindow()),
+                     "map-event", G_CALLBACK(map_event_cb),
+                     menubar.get());
+
+    mMenuBars.AppendElement(menubar.get());
+    RegisterNativeMenuBar(menubar.get());
+
+    static_cast<nsWindow* >(aParent)->SetMenuBar(Move(menubar));
+
+    return NS_OK;
+}
+
+/* static */ already_AddRefed<nsNativeMenuService>
+nsNativeMenuService::GetInstanceForServiceManager() {
+    RefPtr<nsNativeMenuService> service(sService);
+
+    if (service) {
+        return service.forget();
+    }
+
+    service = new nsNativeMenuService();
+
+    if (NS_FAILED(service->Init())) {
+        return nullptr;
+    }
+
+    sService = service.get();
+    return service.forget();
+}
+
+/* static */ nsNativeMenuService*
+nsNativeMenuService::GetSingleton() {
+    EnsureInitialized();
+    return sService;
+}
+
+void
+nsNativeMenuService::NotifyNativeMenuBarDestroyed(nsMenuBar* aMenuBar) {
+    g_signal_handlers_disconnect_by_func(aMenuBar->TopLevelWindow(),
+                                         FuncToGpointer(map_event_cb),
+                                         aMenuBar);
+
+    mMenuBars.RemoveElement(aMenuBar);
+
+    GCancellable* cancellable = nullptr;
+    if (mMenuBarRegistrationCancellables.Get(aMenuBar, &cancellable)) {
+        mMenuBarRegistrationCancellables.Remove(aMenuBar);
+        g_cancellable_cancel(cancellable);
+        g_object_unref(cancellable);
+    }
+}
diff --git a/widget/gtk/nsNativeMenuService.h b/widget/gtk/nsNativeMenuService.h
new file mode 100644
index 000000000..5ce022526
--- /dev/null
+++ b/widget/gtk/nsNativeMenuService.h
@@ -0,0 +1,80 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef __nsNativeMenuService_h__
+#define __nsNativeMenuService_h__
+
+#include "mozilla/Attributes.h"
+#include "nsCOMPtr.h"
+#include "nsDataHashtable.h"
+#include "nsINativeMenuService.h"
+#include "nsTArray.h"
+
+#include <gdk/gdk.h>
+#include <gio/gio.h>
+#include <gtk/gtk.h>
+
+class nsMenuBar;
+
+/*
+ * The main native menu service singleton. nsWebShellWindow calls in to this when
+ * a new top level window is created.
+ *
+ * Menubars are owned by their nsWindow. This service holds a weak reference to
+ * each menubar for the purpose of re-registering them with the shell if it
+ * needs to. The menubar is responsible for notifying the service when the last
+ * reference to it is dropped.
+ */
+class nsNativeMenuService final : public nsINativeMenuService {
+public:
+    NS_DECL_ISUPPORTS
+
+    NS_IMETHOD CreateNativeMenuBar(nsIWidget* aParent, nsIContent* aMenuBarNode) override;
+
+    // Returns the singleton addref'd for the service manager
+    static already_AddRefed<nsNativeMenuService> GetInstanceForServiceManager();
+
+    // Returns the singleton without increasing the reference count
+    static nsNativeMenuService* GetSingleton();
+
+    // Called by a menubar when it is deleted
+    void NotifyNativeMenuBarDestroyed(nsMenuBar* aMenuBar);
+
+private:
+    nsNativeMenuService();
+    ~nsNativeMenuService();
+    nsresult Init();
+
+    static void EnsureInitialized();
+    void SetOnline(bool aOnline);
+    void RegisterNativeMenuBar(nsMenuBar* aMenuBar);
+    static void name_owner_changed_cb(GObject* gobject,
+                                      GParamSpec* pspec,
+                                      gpointer user_data);
+    static void proxy_created_cb(GObject* source_object,
+                                 GAsyncResult* res,
+                                 gpointer user_data);
+    static void register_native_menubar_cb(GObject* source_object,
+                                           GAsyncResult* res,
+                                           gpointer user_data);
+    static gboolean map_event_cb(GtkWidget* widget, GdkEvent* event,
+                                 gpointer user_data);
+    void OnNameOwnerChanged();
+    void OnProxyCreated(GDBusProxy* aProxy);
+    void OnNativeMenuBarRegistered(nsMenuBar* aMenuBar,
+                                   bool aSuccess);
+    static void PrefChangedCallback(const char* aPref, void* aClosure);
+    void PrefChanged();
+
+    GCancellable* mCreateProxyCancellable;
+    GDBusProxy* mDbusProxy;
+    bool mOnline;
+    nsTArray<nsMenuBar* > mMenuBars;
+    nsDataHashtable<nsPtrHashKey<nsMenuBar>, GCancellable*> mMenuBarRegistrationCancellables;
+
+    static bool sShutdown;
+    static nsNativeMenuService* sService;
+};
+
+#endif /* __nsNativeMenuService_h__ */
diff --git a/widget/gtk/nsWidgetFactory.cpp b/widget/gtk/nsWidgetFactory.cpp
index 7e4274377..a1508d1d6 100644
--- a/widget/gtk/nsWidgetFactory.cpp
+++ b/widget/gtk/nsWidgetFactory.cpp
@@ -49,6 +49,8 @@
 #include "GfxInfoX11.h"
 #endif
 
+#include "nsNativeMenuService.h"
+
 #include "nsNativeThemeGTK.h"
 
 #include "nsIComponentRegistrar.h"
@@ -121,6 +123,9 @@ NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(GfxInfo, Init)
 }
 #endif
 
+NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(nsNativeMenuService,
+                                         nsNativeMenuService::GetInstanceForServiceManager)
+
 #ifdef NS_PRINTING
 NS_GENERIC_FACTORY_CONSTRUCTOR(nsDeviceContextSpecGTK)
 NS_GENERIC_FACTORY_CONSTRUCTOR_INIT(nsPrintOptionsGTK, Init)
@@ -223,6 +228,7 @@ NS_DEFINE_NAMED_CID(NS_IMAGE_TO_PIXBUF_CID);
 NS_DEFINE_NAMED_CID(NS_IDLE_SERVICE_CID);
 NS_DEFINE_NAMED_CID(NS_GFXINFO_CID);
 #endif
+NS_DEFINE_NAMED_CID(NS_NATIVEMENUSERVICE_CID);
 
 
 static const mozilla::Module::CIDEntry kWidgetCIDs[] = {
@@ -258,6 +264,7 @@ static const mozilla::Module::CIDEntry kWidgetCIDs[] = {
     { &kNS_IDLE_SERVICE_CID, false, nullptr, nsIdleServiceGTKConstructor },
     { &kNS_GFXINFO_CID, false, nullptr, mozilla::widget::GfxInfoConstructor },
 #endif
+    { &kNS_NATIVEMENUSERVICE_CID, true, NULL, nsNativeMenuServiceConstructor },
     { nullptr }
 };
 
@@ -295,6 +302,7 @@ static const mozilla::Module::ContractIDEntry kWidgetContracts[] = {
     { "@mozilla.org/widget/idleservice;1", &kNS_IDLE_SERVICE_CID },
     { "@mozilla.org/gfx/info;1", &kNS_GFXINFO_CID },
 #endif
+    { "@mozilla.org/widget/nativemenuservice;1", &kNS_NATIVEMENUSERVICE_CID },
     { nullptr }
 };
 
diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index e4e69c1b4..6f222a705 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -67,6 +67,7 @@
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Likely.h"
+#include "mozilla/Move.h"
 #include "mozilla/Preferences.h"
 #include "nsIPrefService.h"
 #include "nsIGConfService.h"
@@ -5175,6 +5176,11 @@ nsWindow::HideWindowChrome(bool aShouldHide)
     return NS_OK;
 }
 
+void
+nsWindow::SetMenuBar(UniquePtr<nsMenuBar> aMenuBar) {
+    mMenuBar = mozilla::Move(aMenuBar);
+}
+
 bool
 nsWindow::CheckForRollup(gdouble aMouseX, gdouble aMouseY,
                          bool aIsWheel, bool aAlwaysRollup)
diff --git a/widget/gtk/nsWindow.h b/widget/gtk/nsWindow.h
index 49a8d4baf..c45176cea 100644
--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -35,6 +35,8 @@
 
 #include "IMContextWrapper.h"
 
+#include "nsMenuBar.h"
+
 #undef LOG
 #ifdef MOZ_LOGGING
 
@@ -162,6 +164,8 @@ public:
                                       nsIScreen* aTargetScreen = nullptr) override;
     NS_IMETHOD         HideWindowChrome(bool aShouldHide) override;
 
+    void               SetMenuBar(mozilla::UniquePtr<nsMenuBar> aMenuBar);
+
     /**
      * GetLastUserInputTime returns a timestamp for the most recent user input
      * event.  This is intended for pointer grab requests (including drags).
@@ -569,6 +573,8 @@ private:
     RefPtr<mozilla::widget::IMContextWrapper> mIMContext;
 
     mozilla::UniquePtr<mozilla::CurrentX11TimeGetter> mCurrentTimeGetter;
+
+    mozilla::UniquePtr<nsMenuBar> mMenuBar;
 };
 
 class nsChildWindow : public nsWindow {
diff --git a/widget/moz.build b/widget/moz.build
index 3ca4c9785..3a52805b0 100644
--- a/widget/moz.build
+++ b/widget/moz.build
@@ -38,10 +38,12 @@ elif toolkit == 'cocoa':
         'nsITaskbarProgress.idl',
     ]
     EXPORTS += [
-        'nsINativeMenuService.h',
         'nsIPrintDialogService.h',
     ]
 
+if toolkit in ('cocoa', 'gtk2', 'gtk3'):
+    EXPORTS += ['nsINativeMenuService.h']
+
 # Don't build the DSO under the 'build' directory as windows does.
 #
 # The DSOs get built in the toolkit dir itself.  Do this so that
diff --git a/xpfe/appshell/nsWebShellWindow.cpp b/xpfe/appshell/nsWebShellWindow.cpp
index f703be728..2893e7868 100644
--- a/xpfe/appshell/nsWebShellWindow.cpp
+++ b/xpfe/appshell/nsWebShellWindow.cpp
@@ -73,7 +73,7 @@
 
 #include "nsPIWindowRoot.h"
 
-#ifdef XP_MACOSX
+#if defined(XP_MACOSX) || defined(MOZ_WIDGET_GTK)
 #include "nsINativeMenuService.h"
 #define USE_NATIVE_MENUS
 #endif