Merge branch 'ext-work'

22 files changed, 2379 insertions, 0 deletions

diff --git a/toolkit/jetpack/sdk/ui/button/action.js b/toolkit/jetpack/sdk/ui/button/action.js
new file mode 100644
index 000000000..dfb092d0c
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/button/action.js
@@ -0,0 +1,114 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '> 28'
+  }
+};
+
+const { Class } = require('../../core/heritage');
+const { merge } = require('../../util/object');
+const { Disposable } = require('../../core/disposable');
+const { on, off, emit, setListeners } = require('../../event/core');
+const { EventTarget } = require('../../event/target');
+const { getNodeView } = require('../../view/core');
+
+const view = require('./view');
+const { buttonContract, stateContract } = require('./contract');
+const { properties, render, state, register, unregister,
+        getDerivedStateFor } = require('../state');
+const { events: stateEvents } = require('../state/events');
+const { events: viewEvents } = require('./view/events');
+const events = require('../../event/utils');
+
+const { getActiveTab } = require('../../tabs/utils');
+
+const { id: addonID } = require('../../self');
+const { identify } = require('../id');
+
+const buttons = new Map();
+
+const toWidgetId = id =>
+  ('action-button--' + addonID.toLowerCase()+ '-' + id).
+    replace(/[^a-z0-9_-]/g, '');
+
+const ActionButton = Class({
+  extends: EventTarget,
+  implements: [
+    properties(stateContract),
+    state(stateContract),
+    Disposable
+  ],
+  setup: function setup(options) {
+    let state = merge({
+      disabled: false
+    }, buttonContract(options));
+
+    let id = toWidgetId(options.id);
+
+    register(this, state);
+
+    // Setup listeners.
+    setListeners(this, options);
+
+    buttons.set(id, this);
+
+    view.create(merge({}, state, { id: id }));
+  },
+
+  dispose: function dispose() {
+    let id = toWidgetId(this.id);
+    buttons.delete(id);
+
+    off(this);
+
+    view.dispose(id);
+
+    unregister(this);
+  },
+
+  get id() {
+    return this.state().id;
+  },
+
+  click: function click() { view.click(toWidgetId(this.id)) }
+});
+exports.ActionButton = ActionButton;
+
+identify.define(ActionButton, ({id}) => toWidgetId(id));
+
+getNodeView.define(ActionButton, button =>
+  view.nodeFor(toWidgetId(button.id))
+);
+
+var actionButtonStateEvents = events.filter(stateEvents,
+  e => e.target instanceof ActionButton);
+
+var actionButtonViewEvents = events.filter(viewEvents,
+  e => buttons.has(e.target));
+
+var clickEvents = events.filter(actionButtonViewEvents, e => e.type === 'click');
+var updateEvents = events.filter(actionButtonViewEvents, e => e.type === 'update');
+
+on(clickEvents, 'data', ({target: id, window}) => {
+  let button = buttons.get(id);
+  let state = getDerivedStateFor(button, getActiveTab(window));
+
+  emit(button, 'click', state);
+});
+
+on(updateEvents, 'data', ({target: id, window}) => {
+  render(buttons.get(id), window);
+});
+
+on(actionButtonStateEvents, 'data', ({target, window, state}) => {
+  let id = toWidgetId(target.id);
+  view.setIcon(id, window, state.icon);
+  view.setLabel(id, window, state.label);
+  view.setDisabled(id, window, state.disabled);
+  view.setBadge(id, window, state.badge, state.badgeColor);
+});
diff --git a/toolkit/jetpack/sdk/ui/button/contract.js b/toolkit/jetpack/sdk/ui/button/contract.js
new file mode 100644
index 000000000..ce6e33d95
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/button/contract.js
@@ -0,0 +1,73 @@
+/* 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/. */
+'use strict';
+
+const { contract } = require('../../util/contract');
+const { isLocalURL } = require('../../url');
+const { isNil, isObject, isString } = require('../../lang/type');
+const { required, either, string, boolean, object, number } = require('../../deprecated/api-utils');
+const { merge } = require('../../util/object');
+const { freeze } = Object;
+
+const isIconSet = (icons) =>
+  Object.keys(icons).
+    every(size => String(size >>> 0) === size && isLocalURL(icons[size]));
+
+var iconSet = {
+  is: either(object, string),
+  map: v => isObject(v) ? freeze(merge({}, v)) : v,
+  ok: v => (isString(v) && isLocalURL(v)) || (isObject(v) && isIconSet(v)),
+  msg: 'The option "icon" must be a local URL or an object with ' +
+    'numeric keys / local URL values pair.'
+}
+
+var id = {
+  is: string,
+  ok: v => /^[a-z-_][a-z0-9-_]*$/i.test(v),
+  msg: 'The option "id" must be a valid alphanumeric id (hyphens and ' +
+        'underscores are allowed).'
+};
+
+var label = {
+  is: string,
+  ok: v => isNil(v) || v.trim().length > 0,
+  msg: 'The option "label" must be a non empty string'
+}
+
+var badge = {
+  is: either(string, number),
+  msg: 'The option "badge" must be a string or a number'
+}
+
+var badgeColor = {
+  is: string,
+  msg: 'The option "badgeColor" must be a string'
+}
+
+var stateContract = contract({
+  label: label,
+  icon: iconSet,
+  disabled: boolean,
+  badge: badge,
+  badgeColor: badgeColor
+});
+
+exports.stateContract = stateContract;
+
+var buttonContract = contract(merge({}, stateContract.rules, {
+  id: required(id),
+  label: required(label),
+  icon: required(iconSet)
+}));
+
+exports.buttonContract = buttonContract;
+
+exports.toggleStateContract = contract(merge({
+  checked: boolean
+}, stateContract.rules));
+
+exports.toggleButtonContract = contract(merge({
+  checked: boolean
+}, buttonContract.rules));
+
diff --git a/toolkit/jetpack/sdk/ui/button/toggle.js b/toolkit/jetpack/sdk/ui/button/toggle.js
new file mode 100644
index 000000000..a226b3212
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/button/toggle.js
@@ -0,0 +1,127 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '> 28'
+  }
+};
+
+const { Class } = require('../../core/heritage');
+const { merge } = require('../../util/object');
+const { Disposable } = require('../../core/disposable');
+const { on, off, emit, setListeners } = require('../../event/core');
+const { EventTarget } = require('../../event/target');
+const { getNodeView } = require('../../view/core');
+
+const view = require('./view');
+const { toggleButtonContract, toggleStateContract } = require('./contract');
+const { properties, render, state, register, unregister,
+  setStateFor, getStateFor, getDerivedStateFor } = require('../state');
+const { events: stateEvents } = require('../state/events');
+const { events: viewEvents } = require('./view/events');
+const events = require('../../event/utils');
+
+const { getActiveTab } = require('../../tabs/utils');
+
+const { id: addonID } = require('../../self');
+const { identify } = require('../id');
+
+const buttons = new Map();
+
+const toWidgetId = id =>
+  ('toggle-button--' + addonID.toLowerCase()+ '-' + id).
+    replace(/[^a-z0-9_-]/g, '');
+
+const ToggleButton = Class({
+  extends: EventTarget,
+  implements: [
+    properties(toggleStateContract),
+    state(toggleStateContract),
+    Disposable
+  ],
+  setup: function setup(options) {
+    let state = merge({
+      disabled: false,
+      checked: false
+    }, toggleButtonContract(options));
+
+    let id = toWidgetId(options.id);
+
+    register(this, state);
+
+    // Setup listeners.
+    setListeners(this, options);
+
+    buttons.set(id, this);
+
+    view.create(merge({ type: 'checkbox' }, state, { id: id }));
+  },
+
+  dispose: function dispose() {
+    let id = toWidgetId(this.id);
+    buttons.delete(id);
+
+    off(this);
+
+    view.dispose(id);
+
+    unregister(this);
+  },
+
+  get id() {
+    return this.state().id;
+  },
+
+  click: function click() {
+    return view.click(toWidgetId(this.id));
+  }
+});
+exports.ToggleButton = ToggleButton;
+
+identify.define(ToggleButton, ({id}) => toWidgetId(id));
+
+getNodeView.define(ToggleButton, button =>
+  view.nodeFor(toWidgetId(button.id))
+);
+
+var toggleButtonStateEvents = events.filter(stateEvents,
+  e => e.target instanceof ToggleButton);
+
+var toggleButtonViewEvents = events.filter(viewEvents,
+  e => buttons.has(e.target));
+
+var clickEvents = events.filter(toggleButtonViewEvents, e => e.type === 'click');
+var updateEvents = events.filter(toggleButtonViewEvents, e => e.type === 'update');
+
+on(toggleButtonStateEvents, 'data', ({target, window, state}) => {
+  let id = toWidgetId(target.id);
+
+  view.setIcon(id, window, state.icon);
+  view.setLabel(id, window, state.label);
+  view.setDisabled(id, window, state.disabled);
+  view.setChecked(id, window, state.checked);
+  view.setBadge(id, window, state.badge, state.badgeColor);
+});
+
+on(clickEvents, 'data', ({target: id, window, checked }) => {
+  let button = buttons.get(id);
+  let windowState = getStateFor(button, window);
+
+  let newWindowState = merge({}, windowState, { checked: checked });
+
+  setStateFor(button, window, newWindowState);
+
+  let state = getDerivedStateFor(button, getActiveTab(window));
+
+  emit(button, 'click', state);
+
+  emit(button, 'change', state);
+});
+
+on(updateEvents, 'data', ({target: id, window}) => {
+  render(buttons.get(id), window);
+});
diff --git a/toolkit/jetpack/sdk/ui/button/view.js b/toolkit/jetpack/sdk/ui/button/view.js
new file mode 100644
index 000000000..63b7aea31
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/button/view.js
@@ -0,0 +1,243 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '> 28'
+  }
+};
+
+const { Cu } = require('chrome');
+const { on, off, emit } = require('../../event/core');
+
+const { data } = require('sdk/self');
+
+const { isObject, isNil } = require('../../lang/type');
+
+const { getMostRecentBrowserWindow } = require('../../window/utils');
+const { ignoreWindow } = require('../../private-browsing/utils');
+const { CustomizableUI } = Cu.import('resource:///modules/CustomizableUI.jsm', {});
+const { AREA_PANEL, AREA_NAVBAR } = CustomizableUI;
+
+const { events: viewEvents } = require('./view/events');
+
+const XUL_NS = 'http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul';
+
+const views = new Map();
+const customizedWindows = new WeakMap();
+
+const buttonListener = {
+  onCustomizeStart: window => {
+    for (let [id, view] of views) {
+      setIcon(id, window, view.icon);
+      setLabel(id, window, view.label);
+    }
+
+    customizedWindows.set(window, true);
+  },
+  onCustomizeEnd: window => {
+    customizedWindows.delete(window);
+
+    for (let [id, ] of views) {
+      let placement = CustomizableUI.getPlacementOfWidget(id);
+
+      if (placement)
+        emit(viewEvents, 'data', { type: 'update', target: id, window: window });
+    }
+  },
+  onWidgetAfterDOMChange: (node, nextNode, container) => {
+    let { id } = node;
+    let view = views.get(id);
+    let window = node.ownerDocument.defaultView;
+
+    if (view) {
+      emit(viewEvents, 'data', { type: 'update', target: id, window: window });
+    }
+  }
+};
+
+CustomizableUI.addListener(buttonListener);
+
+require('../../system/unload').when( _ =>
+  CustomizableUI.removeListener(buttonListener)
+);
+
+function getNode(id, window) {
+  return !views.has(id) || ignoreWindow(window)
+    ? null
+    : CustomizableUI.getWidget(id).forWindow(window).node
+};
+
+function isInToolbar(id) {
+  let placement = CustomizableUI.getPlacementOfWidget(id);
+
+  return placement && CustomizableUI.getAreaType(placement.area) === 'toolbar';
+}
+
+
+function getImage(icon, isInToolbar, pixelRatio) {
+  let targetSize = (isInToolbar ? 18 : 32) * pixelRatio;
+  let bestSize = 0;
+  let image = icon;
+
+  if (isObject(icon)) {
+    for (let size of Object.keys(icon)) {
+      size = +size;
+      let offset = targetSize - size;
+
+      if (offset === 0) {
+        bestSize = size;
+        break;
+      }
+
+      let delta = Math.abs(offset) - Math.abs(targetSize - bestSize);
+
+      if (delta < 0)
+        bestSize = size;
+    }
+
+    image = icon[bestSize];
+  }
+
+  if (image.indexOf('./') === 0)
+    return data.url(image.substr(2));
+
+  return image;
+}
+
+function nodeFor(id, window=getMostRecentBrowserWindow()) {
+  return customizedWindows.has(window) ? null : getNode(id, window);
+};
+exports.nodeFor = nodeFor;
+
+function create(options) {
+  let { id, label, icon, type, badge } = options;
+
+  if (views.has(id))
+    throw new Error('The ID "' + id + '" seems already used.');
+
+  CustomizableUI.createWidget({
+    id: id,
+    type: 'custom',
+    removable: true,
+    defaultArea: AREA_NAVBAR,
+    allowedAreas: [ AREA_PANEL, AREA_NAVBAR ],
+
+    onBuild: function(document) {
+      let window = document.defaultView;
+
+      let node = document.createElementNS(XUL_NS, 'toolbarbutton');
+
+      let image = getImage(icon, true, window.devicePixelRatio);
+
+      if (ignoreWindow(window))
+        node.style.display = 'none';
+
+      node.setAttribute('id', this.id);
+      node.setAttribute('class', 'toolbarbutton-1 chromeclass-toolbar-additional badged-button');
+      node.setAttribute('type', type);
+      node.setAttribute('label', label);
+      node.setAttribute('tooltiptext', label);
+      node.setAttribute('image', image);
+      node.setAttribute('constrain-size', 'true');
+
+      views.set(id, {
+        area: this.currentArea,
+        icon: icon,
+        label: label
+      });
+
+      node.addEventListener('command', function(event) {
+        if (views.has(id)) {
+          emit(viewEvents, 'data', {
+            type: 'click',
+            target: id,
+            window: event.view,
+            checked: node.checked
+          });
+        }
+      });
+
+      return node;
+    }
+  });
+};
+exports.create = create;
+
+function dispose(id) {
+  if (!views.has(id)) return;
+
+  views.delete(id);
+  CustomizableUI.destroyWidget(id);
+}
+exports.dispose = dispose;
+
+function setIcon(id, window, icon) {
+  let node = getNode(id, window);
+
+  if (node) {
+    icon = customizedWindows.has(window) ? views.get(id).icon : icon;
+    let image = getImage(icon, isInToolbar(id), window.devicePixelRatio);
+
+    node.setAttribute('image', image);
+  }
+}
+exports.setIcon = setIcon;
+
+function setLabel(id, window, label) {
+  let node = nodeFor(id, window);
+
+  if (node) {
+    node.setAttribute('label', label);
+    node.setAttribute('tooltiptext', label);
+  }
+}
+exports.setLabel = setLabel;
+
+function setDisabled(id, window, disabled) {
+  let node = nodeFor(id, window);
+
+  if (node)
+    node.disabled = disabled;
+}
+exports.setDisabled = setDisabled;
+
+function setChecked(id, window, checked) {
+  let node = nodeFor(id, window);
+
+  if (node)
+    node.checked = checked;
+}
+exports.setChecked = setChecked;
+
+function setBadge(id, window, badge, color) {
+  let node = nodeFor(id, window);
+
+  if (node) {
+    // `Array.from` is needed to handle unicode symbol properly:
+    // '𝐀𝐁'.length is 4 where Array.from('𝐀𝐁').length is 2
+    let text = isNil(badge)
+                  ? ''
+                  : Array.from(String(badge)).slice(0, 4).join('');
+
+    node.setAttribute('badge', text);
+
+    let badgeNode = node.ownerDocument.getAnonymousElementByAttribute(node,
+                                        'class', 'toolbarbutton-badge');
+
+    if (badgeNode)
+      badgeNode.style.backgroundColor = isNil(color) ? '' : color;
+  }
+}
+exports.setBadge = setBadge;
+
+function click(id) {
+  let node = nodeFor(id);
+
+  if (node)
+    node.click();
+}
+exports.click = click;
diff --git a/toolkit/jetpack/sdk/ui/button/view/events.js b/toolkit/jetpack/sdk/ui/button/view/events.js
new file mode 100644
index 000000000..98909656a
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/button/view/events.js
@@ -0,0 +1,18 @@
+/* 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/. */
+
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '*',
+    'SeaMonkey': '*',
+    'Thunderbird': '*'
+  }
+};
+
+var channel = {};
+
+exports.events = channel;
diff --git a/toolkit/jetpack/sdk/ui/component.js b/toolkit/jetpack/sdk/ui/component.js
new file mode 100644
index 000000000..d1f12c95e
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/component.js
@@ -0,0 +1,182 @@
+/* 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/. */
+"use strict";
+
+// Internal properties not exposed to the public.
+const cache = Symbol("component/cache");
+const writer = Symbol("component/writer");
+const isFirstWrite = Symbol("component/writer/first-write?");
+const currentState = Symbol("component/state/current");
+const pendingState = Symbol("component/state/pending");
+const isWriting = Symbol("component/writing?");
+
+const isntNull = x => x !== null;
+
+const Component = function(options, children) {
+  this[currentState] = null;
+  this[pendingState] = null;
+  this[writer] = null;
+  this[cache] = null;
+  this[isFirstWrite] = true;
+
+  this[Component.construct](options, children);
+}
+Component.Component = Component;
+// Constructs component.
+Component.construct = Symbol("component/construct");
+// Called with `options` and `children` and must return
+// initial state back.
+Component.initial = Symbol("component/initial");
+
+// Function patches current `state` with a given update.
+Component.patch = Symbol("component/patch");
+// Function that replaces current `state` with a passed state.
+Component.reset = Symbol("component/reset");
+
+// Function that must return render tree from passed state.
+Component.render = Symbol("component/render");
+
+// Path of the component with in the mount point.
+Component.path = Symbol("component/path");
+
+Component.isMounted = component => !!component[writer];
+Component.isWriting = component => !!component[isWriting];
+
+// Internal method that mounts component to a writer.
+// Mounts component to a writer.
+Component.mount = (component, write) => {
+  if (Component.isMounted(component)) {
+    throw Error("Can not mount already mounted component");
+  }
+
+  component[writer] = write;
+  Component.write(component);
+
+  if (component[Component.mounted]) {
+    component[Component.mounted]();
+  }
+}
+
+// Unmounts component from a writer.
+Component.unmount = (component) => {
+  if (Component.isMounted(component)) {
+    component[writer] = null;
+    if (component[Component.unmounted]) {
+      component[Component.unmounted]();
+    }
+  } else {
+    console.warn("Unmounting component that is not mounted is redundant");
+  }
+};
+ // Method invoked once after inital write occurs.
+Component.mounted = Symbol("component/mounted");
+// Internal method that unmounts component from the writer.
+Component.unmounted = Symbol("component/unmounted");
+// Function that must return true if component is changed
+Component.isUpdated = Symbol("component/updated?");
+Component.update = Symbol("component/update");
+Component.updated = Symbol("component/updated");
+
+const writeChild = base => (child, index) => Component.write(child, base, index)
+Component.write = (component, base, index) => {
+  if (component === null) {
+    return component;
+  }
+
+  if (!(component instanceof Component)) {
+    const path = base ? `${base}${component.key || index}/` : `/`;
+    return Object.assign({}, component, {
+      [Component.path]: path,
+      children: component.children && component.children.
+                                        map(writeChild(path)).
+                                        filter(isntNull)
+    });
+  }
+
+  component[isWriting] = true;
+
+  try {
+
+    const current = component[currentState];
+    const pending = component[pendingState] || current;
+    const isUpdated = component[Component.isUpdated];
+    const isInitial = component[isFirstWrite];
+
+    if (isUpdated(current, pending) || isInitial) {
+      if (!isInitial && component[Component.update]) {
+        component[Component.update](pending, current)
+      }
+
+      // Note: [Component.update] could have caused more updates so can't use
+      // `pending` as `component[pendingState]` may have changed.
+      component[currentState] = component[pendingState] || current;
+      component[pendingState] = null;
+
+      const tree = component[Component.render](component[currentState]);
+      component[cache] = Component.write(tree, base, index);
+      if (component[writer]) {
+        component[writer].call(null, component[cache]);
+      }
+
+      if (!isInitial && component[Component.updated]) {
+        component[Component.updated](current, pending);
+      }
+    }
+
+    component[isFirstWrite] = false;
+
+    return component[cache];
+  } finally {
+    component[isWriting] = false;
+  }
+};
+
+Component.prototype = Object.freeze({
+  constructor: Component,
+
+  [Component.mounted]: null,
+  [Component.unmounted]: null,
+  [Component.update]: null,
+  [Component.updated]: null,
+
+  get state() {
+    return this[pendingState] || this[currentState];
+  },
+
+
+  [Component.construct](settings, items) {
+    const initial = this[Component.initial];
+    const base = initial(settings, items);
+    const options = Object.assign(Object.create(null), base.options, settings);
+    const children = base.children || items || null;
+    const state = Object.assign(Object.create(null), base, {options, children});
+    this[currentState] = state;
+
+    if (this.setup) {
+      this.setup(state);
+    }
+  },
+  [Component.initial](options, children) {
+    return Object.create(null);
+  },
+  [Component.patch](update) {
+    this[Component.reset](Object.assign({}, this.state, update));
+  },
+  [Component.reset](state) {
+    this[pendingState] = state;
+    if (Component.isMounted(this) && !Component.isWriting(this)) {
+      Component.write(this);
+    }
+  },
+
+  [Component.isUpdated](before, after) {
+    return before != after
+  },
+
+  [Component.render](state) {
+    throw Error("Component must implement [Component.render] member");
+  }
+});
+
+module.exports = Component;
diff --git a/toolkit/jetpack/sdk/ui/frame.js b/toolkit/jetpack/sdk/ui/frame.js
new file mode 100644
index 000000000..566353cdf
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/frame.js
@@ -0,0 +1,16 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+require("./frame/view");
+const { Frame } = require("./frame/model");
+
+exports.Frame = Frame;
diff --git a/toolkit/jetpack/sdk/ui/frame/model.js b/toolkit/jetpack/sdk/ui/frame/model.js
new file mode 100644
index 000000000..627310874
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/frame/model.js
@@ -0,0 +1,154 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+const { Class } = require("../../core/heritage");
+const { EventTarget } = require("../../event/target");
+const { emit, off, setListeners } = require("../../event/core");
+const { Reactor, foldp, send, merges } = require("../../event/utils");
+const { Disposable } = require("../../core/disposable");
+const { OutputPort } = require("../../output/system");
+const { InputPort } = require("../../input/system");
+const { identify } = require("../id");
+const { pairs, object, map, each } = require("../../util/sequence");
+const { patch, diff } = require("diffpatcher/index");
+const { isLocalURL } = require("../../url");
+const { compose } = require("../../lang/functional");
+const { contract } = require("../../util/contract");
+const { id: addonID, data: { url: resolve }} = require("../../self");
+const { Frames } = require("../../input/frame");
+
+
+const output = new OutputPort({ id: "frame-change" });
+const mailbox = new OutputPort({ id: "frame-mailbox" });
+const input = Frames;
+
+
+const makeID = url =>
+  ("frame-" + addonID + "-" + url).
+    split("/").join("-").
+    split(".").join("-").
+    replace(/[^A-Za-z0-9_\-]/g, "");
+
+const validate = contract({
+  name: {
+    is: ["string", "undefined"],
+    ok: x => /^[a-z][a-z0-9-_]+$/i.test(x),
+    msg: "The `option.name` must be a valid alphanumeric string (hyphens and " +
+         "underscores are allowed) starting with letter."
+  },
+  url: {
+    map: x => x.toString(),
+    is: ["string"],
+    ok: x => isLocalURL(x),
+    msg: "The `options.url` must be a valid local URI."
+  }
+});
+
+const Source = function({id, ownerID}) {
+  this.id = id;
+  this.ownerID = ownerID;
+};
+Source.postMessage = ({id, ownerID}, data, origin) => {
+  send(mailbox, object([id, {
+    inbox: {
+      target: {id: id, ownerID: ownerID},
+      timeStamp: Date.now(),
+      data: data,
+      origin: origin
+    }
+  }]));
+};
+Source.prototype.postMessage = function(data, origin) {
+  Source.postMessage(this, data, origin);
+};
+
+const Message = function({type, data, source, origin, timeStamp}) {
+  this.type = type;
+  this.data = data;
+  this.origin = origin;
+  this.timeStamp = timeStamp;
+  this.source = new Source(source);
+};
+
+
+const frames = new Map();
+const sources = new Map();
+
+const Frame = Class({
+  extends: EventTarget,
+  implements: [Disposable, Source],
+  initialize: function(params={}) {
+    const options = validate(params);
+    const id = makeID(options.name || options.url);
+
+    if (frames.has(id))
+      throw Error("Frame with this id already exists: " + id);
+
+    const initial = { id: id, url: resolve(options.url) };
+    this.id = id;
+
+    setListeners(this, params);
+
+    frames.set(this.id, this);
+
+    send(output, object([id, initial]));
+  },
+  get url() {
+    const state = reactor.value[this.id];
+    return state && state.url;
+  },
+  destroy: function() {
+    send(output, object([this.id, null]));
+    frames.delete(this.id);
+    off(this);
+  },
+  // `JSON.stringify` serializes objects based of the return
+  // value of this method. For convinienc we provide this method
+  // to serialize actual state data.
+  toJSON: function() {
+    return { id: this.id, url: this.url };
+  }
+});
+identify.define(Frame, frame => frame.id);
+
+exports.Frame = Frame;
+
+const reactor = new Reactor({
+  onStep: (present, past) => {
+    const delta = diff(past, present);
+
+    each(([id, update]) => {
+      const frame = frames.get(id);
+      if (update) {
+        if (!past[id])
+          emit(frame, "register");
+
+        if (update.outbox)
+          emit(frame, "message", new Message(present[id].outbox));
+
+        each(([ownerID, state]) => {
+          const readyState = state ? state.readyState : "detach";
+          const type = readyState === "loading" ? "attach" :
+                       readyState === "interactive" ? "ready" :
+                       readyState === "complete" ? "load" :
+                       readyState;
+
+          // TODO: Cache `Source` instances somewhere to preserve
+          // identity.
+          emit(frame, type, {type: type,
+                             source: new Source({id: id, ownerID: ownerID})});
+        }, pairs(update.owners));
+      }
+    }, pairs(delta));
+  }
+});
+reactor.run(input);
diff --git a/toolkit/jetpack/sdk/ui/frame/view.html b/toolkit/jetpack/sdk/ui/frame/view.html
new file mode 100644
index 000000000..2a405b583
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/frame/view.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <script>
+      // HACK: This is not an ideal way to deliver chrome messages
+      // to an inner frame content but seems only way that would
+      // make `event.source` this (outer frame) window.
+      window.onmessage = function(event) {
+        var frame = document.querySelector("iframe");
+        var content = frame.contentWindow;
+        // If message is posted from chrome it has no `event.source`.
+        if (event.source === null)
+          content.postMessage(event.data, "*");
+      };
+    </script>
+  </head>
+  <body style="overflow: hidden"></body>
+</html>
diff --git a/toolkit/jetpack/sdk/ui/frame/view.js b/toolkit/jetpack/sdk/ui/frame/view.js
new file mode 100644
index 000000000..2eb4df2b7
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/frame/view.js
@@ -0,0 +1,150 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+const { Cu, Ci } = require("chrome");
+const { CustomizableUI } = Cu.import('resource:///modules/CustomizableUI.jsm', {});
+const { subscribe, send, Reactor, foldp, lift, merges, keepIf } = require("../../event/utils");
+const { InputPort } = require("../../input/system");
+const { OutputPort } = require("../../output/system");
+const { LastClosed } = require("../../input/browser");
+const { pairs, keys, object, each } = require("../../util/sequence");
+const { curry, compose } = require("../../lang/functional");
+const { getFrameElement, getOuterId,
+        getByOuterId, getOwnerBrowserWindow } = require("../../window/utils");
+const { patch, diff } = require("diffpatcher/index");
+const { encode } = require("../../base64");
+const { Frames } = require("../../input/frame");
+
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+const HTML_NS = "http://www.w3.org/1999/xhtml";
+const OUTER_FRAME_URI = module.uri.replace(/\.js$/, ".html");
+
+const mailbox = new OutputPort({ id: "frame-mailbox" });
+
+const frameID = frame => frame.id.replace("outer-", "");
+const windowID = compose(getOuterId, getOwnerBrowserWindow);
+
+const getOuterFrame = (windowID, frameID) =>
+    getByOuterId(windowID).document.getElementById("outer-" + frameID);
+
+const listener = ({target, source, data, origin, timeStamp}) => {
+  // And sent received message to outbox so that frame API model
+  // will deal with it.
+  if (source && source !== target) {
+    const frame = getFrameElement(target);
+    const id = frameID(frame);
+    send(mailbox, object([id, {
+      outbox: {type: "message",
+               source: {id: id, ownerID: windowID(frame)},
+               data: data,
+               origin: origin,
+               timeStamp: timeStamp}}]));
+  }
+};
+
+// Utility function used to create frame with a given `state` and
+// inject it into given `window`.
+const registerFrame = ({id, url}) => {
+  CustomizableUI.createWidget({
+    id: id,
+    type: "custom",
+    removable: true,
+    onBuild: document => {
+      let view = document.createElementNS(XUL_NS, "toolbaritem");
+      view.setAttribute("id", id);
+      view.setAttribute("flex", 2);
+
+      let outerFrame = document.createElementNS(XUL_NS, "iframe");
+      outerFrame.setAttribute("src", OUTER_FRAME_URI);
+      outerFrame.setAttribute("id", "outer-" + id);
+      outerFrame.setAttribute("data-is-sdk-outer-frame", true);
+      outerFrame.setAttribute("type", "content");
+      outerFrame.setAttribute("transparent", true);
+      outerFrame.setAttribute("flex", 2);
+      outerFrame.setAttribute("style", "overflow: hidden;");
+      outerFrame.setAttribute("scrolling", "no");
+      outerFrame.setAttribute("disablehistory", true);
+      outerFrame.setAttribute("seamless", "seamless");
+      outerFrame.addEventListener("load", function onload() {
+        outerFrame.removeEventListener("load", onload, true);
+
+        let doc = outerFrame.contentDocument;
+
+        let innerFrame = doc.createElementNS(HTML_NS, "iframe");
+        innerFrame.setAttribute("id", id);
+        innerFrame.setAttribute("src", url);
+        innerFrame.setAttribute("seamless", "seamless");
+        innerFrame.setAttribute("sandbox", "allow-scripts");
+        innerFrame.setAttribute("scrolling", "no");
+        innerFrame.setAttribute("data-is-sdk-inner-frame", true);
+        innerFrame.setAttribute("style", [ "border:none",
+          "position:absolute", "width:100%", "top: 0",
+          "left: 0", "overflow: hidden"].join(";"));
+
+        doc.body.appendChild(innerFrame);
+      }, true);
+
+      view.appendChild(outerFrame);
+
+      return view;
+    }
+  });
+};
+
+const unregisterFrame = CustomizableUI.destroyWidget;
+
+const deliverMessage = curry((frameID, data, windowID) => {
+  const frame = getOuterFrame(windowID, frameID);
+  const content = frame && frame.contentWindow;
+
+  if (content)
+    content.postMessage(data, content.location.origin);
+});
+
+const updateFrame = (id, {inbox, owners}, present) => {
+  if (inbox) {
+    const { data, target:{ownerID}, source } = present[id].inbox;
+    if (ownerID)
+      deliverMessage(id, data, ownerID);
+    else
+      each(deliverMessage(id, data), keys(present[id].owners));
+  }
+
+  each(setupView(id), pairs(owners));
+};
+
+const setupView = curry((frameID, [windowID, state]) => {
+  if (state && state.readyState === "loading") {
+    const frame = getOuterFrame(windowID, frameID);
+    // Setup a message listener on contentWindow.
+    frame.contentWindow.addEventListener("message", listener);
+  }
+});
+
+
+const reactor = new Reactor({
+  onStep: (present, past) => {
+    const delta = diff(past, present);
+
+    // Apply frame changes
+    each(([id, update]) => {
+      if (update === null)
+        unregisterFrame(id);
+      else if (past[id])
+        updateFrame(id, update, present);
+      else
+        registerFrame(update);
+    }, pairs(delta));
+  },
+  onEnd: state => each(unregisterFrame, keys(state))
+});
+reactor.run(Frames);
diff --git a/toolkit/jetpack/sdk/ui/id.js b/toolkit/jetpack/sdk/ui/id.js
new file mode 100644
index 000000000..d17eb0a4e
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/id.js
@@ -0,0 +1,27 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental'
+};
+
+const method = require('../../method/core');
+const { uuid } = require('../util/uuid');
+
+// NOTE: use lang/functional memoize when it is updated to use WeakMap
+function memoize(f) {
+  const memo = new WeakMap();
+
+  return function memoizer(o) {
+    let key = o;
+    if (!memo.has(key))
+      memo.set(key, f.apply(this, arguments));
+    return memo.get(key);
+  };
+}
+
+var identify = method('identify');
+identify.define(Object, memoize(function() { return uuid(); }));
+exports.identify = identify;
diff --git a/toolkit/jetpack/sdk/ui/sidebar.js b/toolkit/jetpack/sdk/ui/sidebar.js
new file mode 100644
index 000000000..59e35ea11
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar.js
@@ -0,0 +1,311 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '*'
+  }
+};
+
+const { Class } = require('../core/heritage');
+const { merge } = require('../util/object');
+const { Disposable } = require('../core/disposable');
+const { off, emit, setListeners } = require('../event/core');
+const { EventTarget } = require('../event/target');
+const { URL } = require('../url');
+const { add, remove, has, clear, iterator } = require('../lang/weak-set');
+const { id: addonID, data } = require('../self');
+const { WindowTracker } = require('../deprecated/window-utils');
+const { isShowing } = require('./sidebar/utils');
+const { isBrowser, getMostRecentBrowserWindow, windows, isWindowPrivate } = require('../window/utils');
+const { ns } = require('../core/namespace');
+const { remove: removeFromArray } = require('../util/array');
+const { show, hide, toggle } = require('./sidebar/actions');
+const { Worker } = require('../deprecated/sync-worker');
+const { contract: sidebarContract } = require('./sidebar/contract');
+const { create, dispose, updateTitle, updateURL, isSidebarShowing, showSidebar, hideSidebar } = require('./sidebar/view');
+const { defer } = require('../core/promise');
+const { models, views, viewsFor, modelFor } = require('./sidebar/namespace');
+const { isLocalURL } = require('../url');
+const { ensure } = require('../system/unload');
+const { identify } = require('./id');
+const { uuid } = require('../util/uuid');
+const { viewFor } = require('../view/core');
+
+const resolveURL = (url) => url ? data.url(url) : url;
+
+const sidebarNS = ns();
+
+const WEB_PANEL_BROWSER_ID = 'web-panels-browser';
+
+var sidebars = {};
+
+const Sidebar = Class({
+  implements: [ Disposable ],
+  extends: EventTarget,
+  setup: function(options) {
+    // inital validation for the model information
+    let model = sidebarContract(options);
+
+    // save the model information
+    models.set(this, model);
+
+    // generate an id if one was not provided
+    model.id = model.id || addonID + '-' + uuid();
+
+    // further validation for the title and url
+    validateTitleAndURLCombo({}, this.title, this.url);
+
+    const self = this;
+    const internals = sidebarNS(self);
+    const windowNS = internals.windowNS = ns();
+
+    // see bug https://bugzilla.mozilla.org/show_bug.cgi?id=886148
+    ensure(this, 'destroy');
+
+    setListeners(this, options);
+
+    let bars = [];
+    internals.tracker = WindowTracker({
+      onTrack: function(window) {
+        if (!isBrowser(window))
+          return;
+
+        let sidebar = window.document.getElementById('sidebar');
+        let sidebarBox = window.document.getElementById('sidebar-box');
+
+        let bar = create(window, {
+          id: self.id,
+          title: self.title,
+          sidebarurl: self.url
+        });
+        bars.push(bar);
+        windowNS(window).bar = bar;
+
+        bar.addEventListener('command', function() {
+          if (isSidebarShowing(window, self)) {
+            hideSidebar(window, self).catch(() => {});
+            return;
+          }
+
+          showSidebar(window, self);
+        }, false);
+
+        function onSidebarLoad() {
+          // check if the sidebar is ready
+          let isReady = sidebar.docShell && sidebar.contentDocument;
+          if (!isReady)
+            return;
+
+          // check if it is a web panel
+          let panelBrowser = sidebar.contentDocument.getElementById(WEB_PANEL_BROWSER_ID);
+          if (!panelBrowser) {
+            bar.removeAttribute('checked');
+            return;
+          }
+
+          let sbTitle = window.document.getElementById('sidebar-title');
+          function onWebPanelSidebarCreated() {
+            if (panelBrowser.contentWindow.location != resolveURL(model.url) ||
+                sbTitle.value != model.title) {
+              return;
+            }
+
+            let worker = windowNS(window).worker = Worker({
+              window: panelBrowser.contentWindow,
+              injectInDocument: true
+            });
+
+            function onWebPanelSidebarUnload() {
+              windowNS(window).onWebPanelSidebarUnload = null;
+
+              // uncheck the associated menuitem
+              bar.setAttribute('checked', 'false');
+
+              emit(self, 'hide', {});
+              emit(self, 'detach', worker);
+              windowNS(window).worker = null;
+            }
+            windowNS(window).onWebPanelSidebarUnload = onWebPanelSidebarUnload;
+            panelBrowser.contentWindow.addEventListener('unload', onWebPanelSidebarUnload, true);
+
+            // check the associated menuitem
+            bar.setAttribute('checked', 'true');
+
+            function onWebPanelSidebarReady() {
+              panelBrowser.contentWindow.removeEventListener('DOMContentLoaded', onWebPanelSidebarReady, false);
+              windowNS(window).onWebPanelSidebarReady = null;
+
+              emit(self, 'ready', worker);
+            }
+            windowNS(window).onWebPanelSidebarReady = onWebPanelSidebarReady;
+            panelBrowser.contentWindow.addEventListener('DOMContentLoaded', onWebPanelSidebarReady, false);
+
+            function onWebPanelSidebarLoad() {
+              panelBrowser.contentWindow.removeEventListener('load', onWebPanelSidebarLoad, true);
+              windowNS(window).onWebPanelSidebarLoad = null;
+
+              // TODO: decide if returning worker is acceptable..
+              //emit(self, 'show', { worker: worker });
+              emit(self, 'show', {});
+            }
+            windowNS(window).onWebPanelSidebarLoad = onWebPanelSidebarLoad;
+            panelBrowser.contentWindow.addEventListener('load', onWebPanelSidebarLoad, true);
+
+            emit(self, 'attach', worker);
+          }
+          windowNS(window).onWebPanelSidebarCreated = onWebPanelSidebarCreated;
+          panelBrowser.addEventListener('DOMWindowCreated', onWebPanelSidebarCreated, true);
+        }
+        windowNS(window).onSidebarLoad = onSidebarLoad;
+        sidebar.addEventListener('load', onSidebarLoad, true); // removed properly
+      },
+      onUntrack: function(window) {
+        if (!isBrowser(window))
+          return;
+
+        // hide the sidebar if it is showing
+        hideSidebar(window, self).catch(() => {});
+
+        // kill the menu item
+        let { bar } = windowNS(window);
+        if (bar) {
+          removeFromArray(viewsFor(self), bar);
+          dispose(bar);
+        }
+
+        // kill listeners
+        let sidebar = window.document.getElementById('sidebar');
+
+        if (windowNS(window).onSidebarLoad) {
+          sidebar && sidebar.removeEventListener('load', windowNS(window).onSidebarLoad, true)
+          windowNS(window).onSidebarLoad = null;
+        }
+
+        let panelBrowser = sidebar && sidebar.contentDocument.getElementById(WEB_PANEL_BROWSER_ID);
+        if (windowNS(window).onWebPanelSidebarCreated) {
+          panelBrowser && panelBrowser.removeEventListener('DOMWindowCreated', windowNS(window).onWebPanelSidebarCreated, true);
+          windowNS(window).onWebPanelSidebarCreated = null;
+        }
+
+        if (windowNS(window).onWebPanelSidebarReady) {
+          panelBrowser && panelBrowser.contentWindow.removeEventListener('DOMContentLoaded', windowNS(window).onWebPanelSidebarReady, false);
+          windowNS(window).onWebPanelSidebarReady = null;
+        }
+
+        if (windowNS(window).onWebPanelSidebarLoad) {
+          panelBrowser && panelBrowser.contentWindow.removeEventListener('load', windowNS(window).onWebPanelSidebarLoad, true);
+          windowNS(window).onWebPanelSidebarLoad = null;
+        }
+
+        if (windowNS(window).onWebPanelSidebarUnload) {
+          panelBrowser && panelBrowser.contentWindow.removeEventListener('unload', windowNS(window).onWebPanelSidebarUnload, true);
+          windowNS(window).onWebPanelSidebarUnload();
+        }
+      }
+    });
+
+    views.set(this, bars);
+
+    add(sidebars, this);
+  },
+  get id() {
+    return (modelFor(this) || {}).id;
+  },
+  get title() {
+    return (modelFor(this) || {}).title;
+  },
+  set title(v) {
+    // destroyed?
+    if (!modelFor(this))
+      return;
+    // validation
+    if (typeof v != 'string')
+      throw Error('title must be a string');
+    validateTitleAndURLCombo(this, v, this.url);
+    // do update
+    updateTitle(this, v);
+    return modelFor(this).title = v;
+  },
+  get url() {
+    return (modelFor(this) || {}).url;
+  },
+  set url(v) {
+    // destroyed?
+    if (!modelFor(this))
+      return;
+
+    // validation
+    if (!isLocalURL(v))
+      throw Error('the url must be a valid local url');
+
+    validateTitleAndURLCombo(this, this.title, v);
+
+    // do update
+    updateURL(this, v);
+    modelFor(this).url = v;
+  },
+  show: function(window) {
+    return showSidebar(viewFor(window), this);
+  },
+  hide: function(window) {
+    return hideSidebar(viewFor(window), this);
+  },
+  dispose: function() {
+    const internals = sidebarNS(this);
+
+    off(this);
+
+    remove(sidebars, this);
+
+    // stop tracking windows
+    if (internals.tracker) {
+      internals.tracker.unload();
+    }
+
+    internals.tracker = null;
+    internals.windowNS = null;
+
+    views.delete(this);
+    models.delete(this);
+  }
+});
+exports.Sidebar = Sidebar;
+
+function validateTitleAndURLCombo(sidebar, title, url) {
+  url = resolveURL(url);
+
+  if (sidebar.title == title && sidebar.url == url) {
+    return false;
+  }
+
+  for (let window of windows(null, { includePrivate: true })) {
+    let sidebar = window.document.querySelector('menuitem[sidebarurl="' + url + '"][label="' + title + '"]');
+    if (sidebar) {
+      throw Error('The provided title and url combination is invalid (already used).');
+    }
+  }
+
+  return false;
+}
+
+isShowing.define(Sidebar, isSidebarShowing.bind(null, null));
+show.define(Sidebar, showSidebar.bind(null, null));
+hide.define(Sidebar, hideSidebar.bind(null, null));
+
+identify.define(Sidebar, function(sidebar) {
+  return sidebar.id;
+});
+
+function toggleSidebar(window, sidebar) {
+  // TODO: make sure this is not private
+  window = window || getMostRecentBrowserWindow();
+  if (isSidebarShowing(window, sidebar)) {
+    return hideSidebar(window, sidebar);
+  }
+  return showSidebar(window, sidebar);
+}
+toggle.define(Sidebar, toggleSidebar.bind(null, null));
diff --git a/toolkit/jetpack/sdk/ui/sidebar/actions.js b/toolkit/jetpack/sdk/ui/sidebar/actions.js
new file mode 100644
index 000000000..4a52984c9
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar/actions.js
@@ -0,0 +1,10 @@
+/* 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/. */
+'use strict';
+
+const method = require('../../../method/core');
+
+exports.show = method('show');
+exports.hide = method('hide');
+exports.toggle = method('toggle');
diff --git a/toolkit/jetpack/sdk/ui/sidebar/contract.js b/toolkit/jetpack/sdk/ui/sidebar/contract.js
new file mode 100644
index 000000000..b59c37c0b
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar/contract.js
@@ -0,0 +1,27 @@
+/* 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/. */
+'use strict';
+
+const { contract } = require('../../util/contract');
+const { isValidURI, URL, isLocalURL } = require('../../url');
+const { isNil, isObject, isString } = require('../../lang/type');
+
+exports.contract = contract({
+  id: {
+  	is: [ 'string', 'undefined' ],
+  	ok: v => /^[a-z0-9-_]+$/i.test(v),
+    msg: 'The option "id" must be a valid alphanumeric id (hyphens and ' +
+         'underscores are allowed).'
+  },
+  title: {
+  	is: [ 'string' ],
+  	ok: v => v.length
+  },
+  url: {
+    is: [ 'string' ],
+    ok: v => isLocalURL(v),
+    map: v => v.toString(),
+    msg: 'The option "url" must be a valid local URI.'
+  }
+});
diff --git a/toolkit/jetpack/sdk/ui/sidebar/namespace.js b/toolkit/jetpack/sdk/ui/sidebar/namespace.js
new file mode 100644
index 000000000..d79725d1a
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar/namespace.js
@@ -0,0 +1,15 @@
+/* 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/. */
+'use strict';
+
+const models = exports.models = new WeakMap();
+const views = exports.views = new WeakMap();
+exports.buttons = new WeakMap();
+
+exports.viewsFor = function viewsFor(sidebar) {
+  return views.get(sidebar);
+};
+exports.modelFor = function modelFor(sidebar) {
+  return models.get(sidebar);
+};
diff --git a/toolkit/jetpack/sdk/ui/sidebar/utils.js b/toolkit/jetpack/sdk/ui/sidebar/utils.js
new file mode 100644
index 000000000..d6145c32e
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar/utils.js
@@ -0,0 +1,8 @@
+/* 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/. */
+'use strict';
+
+const method = require('../../../method/core');
+
+exports.isShowing = method('isShowing');
diff --git a/toolkit/jetpack/sdk/ui/sidebar/view.js b/toolkit/jetpack/sdk/ui/sidebar/view.js
new file mode 100644
index 000000000..c91e69d3d
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/sidebar/view.js
@@ -0,0 +1,214 @@
+/* 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/. */
+'use strict';
+
+module.metadata = {
+  'stability': 'unstable',
+  'engines': {
+    'Firefox': '*'
+  }
+};
+
+const { models, buttons, views, viewsFor, modelFor } = require('./namespace');
+const { isBrowser, getMostRecentBrowserWindow, windows, isWindowPrivate } = require('../../window/utils');
+const { setStateFor } = require('../state');
+const { defer } = require('../../core/promise');
+const { isPrivateBrowsingSupported, data } = require('../../self');
+
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+const WEB_PANEL_BROWSER_ID = 'web-panels-browser';
+
+const resolveURL = (url) => url ? data.url(url) : url;
+
+function create(window, details) {
+  let id = makeID(details.id);
+  let { document } = window;
+
+  if (document.getElementById(id))
+    throw new Error('The ID "' + details.id + '" seems already used.');
+
+  let menuitem = document.createElementNS(XUL_NS, 'menuitem');
+  menuitem.setAttribute('id', id);
+  menuitem.setAttribute('label', details.title);
+  menuitem.setAttribute('sidebarurl', resolveURL(details.sidebarurl));
+  menuitem.setAttribute('checked', 'false');
+  menuitem.setAttribute('type', 'checkbox');
+  menuitem.setAttribute('group', 'sidebar');
+  menuitem.setAttribute('autoCheck', 'false');
+
+  document.getElementById('viewSidebarMenu').appendChild(menuitem);
+
+  return menuitem;
+}
+exports.create = create;
+
+function dispose(menuitem) {
+  menuitem.parentNode.removeChild(menuitem);
+}
+exports.dispose = dispose;
+
+function updateTitle(sidebar, title) {
+  let button = buttons.get(sidebar);
+
+  for (let window of windows(null, { includePrivate: true })) {
+  	let { document } = window;
+
+    // update the button
+    if (button) {
+      setStateFor(button, window, { label: title });
+    }
+
+    // update the menuitem
+    let mi = document.getElementById(makeID(sidebar.id));
+    if (mi) {
+      mi.setAttribute('label', title)
+    }
+
+    // update sidebar, if showing
+    if (isSidebarShowing(window, sidebar)) {
+      document.getElementById('sidebar-title').setAttribute('value', title);
+    }
+  }
+}
+exports.updateTitle = updateTitle;
+
+function updateURL(sidebar, url) {
+  let eleID = makeID(sidebar.id);
+
+  url = resolveURL(url);
+
+  for (let window of windows(null, { includePrivate: true })) {
+    // update the menuitem
+    let mi = window.document.getElementById(eleID);
+    if (mi) {
+      mi.setAttribute('sidebarurl', url)
+    }
+
+    // update sidebar, if showing
+    if (isSidebarShowing(window, sidebar)) {
+      showSidebar(window, sidebar, url);
+    }
+  }
+}
+exports.updateURL = updateURL;
+
+function isSidebarShowing(window, sidebar) {
+  let win = window || getMostRecentBrowserWindow();
+
+  // make sure there is a window
+  if (!win) {
+    return false;
+  }
+
+  // make sure there is a sidebar for the window
+  let sb = win.document.getElementById('sidebar');
+  let sidebarTitle = win.document.getElementById('sidebar-title');
+  if (!(sb && sidebarTitle)) {
+    return false;
+  }
+
+  // checks if the sidebar box is hidden
+  let sbb = win.document.getElementById('sidebar-box');
+  if (!sbb || sbb.hidden) {
+    return false;
+  }
+
+  if (sidebarTitle.value == modelFor(sidebar).title) {
+    let url = resolveURL(modelFor(sidebar).url);
+
+    // checks if the sidebar is loading
+    if (win.gWebPanelURI == url) {
+      return true;
+    }
+
+    // checks if the sidebar loaded already
+    let ele = sb.contentDocument && sb.contentDocument.getElementById(WEB_PANEL_BROWSER_ID);
+    if (!ele) {
+      return false;
+    }
+
+    if (ele.getAttribute('cachedurl') == url) {
+      return true;
+    }
+
+    if (ele && ele.contentWindow && ele.contentWindow.location == url) {
+      return true;
+    }
+  }
+
+  // default
+  return false;
+}
+exports.isSidebarShowing = isSidebarShowing;
+
+function showSidebar(window, sidebar, newURL) {
+  window = window || getMostRecentBrowserWindow();
+
+  let { promise, resolve, reject } = defer();
+  let model = modelFor(sidebar);
+
+  if (!newURL && isSidebarShowing(window, sidebar)) {
+    resolve({});
+  }
+  else if (!isPrivateBrowsingSupported && isWindowPrivate(window)) {
+    reject(Error('You cannot show a sidebar on private windows'));
+  }
+  else {
+    sidebar.once('show', resolve);
+
+    let menuitem = window.document.getElementById(makeID(model.id));
+    menuitem.setAttribute('checked', true);
+
+    window.openWebPanel(model.title, resolveURL(newURL || model.url));
+  }
+
+  return promise;
+}
+exports.showSidebar = showSidebar;
+
+
+function hideSidebar(window, sidebar) {
+  window = window || getMostRecentBrowserWindow();
+
+  let { promise, resolve, reject } = defer();
+
+  if (!isSidebarShowing(window, sidebar)) {
+    reject(Error('The sidebar is already hidden'));
+  }
+  else {
+    sidebar.once('hide', resolve);
+
+    // Below was taken from http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser.js#4775
+    // the code for window.todggleSideBar()..
+    let { document } = window;
+    let sidebarEle = document.getElementById('sidebar');
+    let sidebarTitle = document.getElementById('sidebar-title');
+    let sidebarBox = document.getElementById('sidebar-box');
+    let sidebarSplitter = document.getElementById('sidebar-splitter');
+    let commandID = sidebarBox.getAttribute('sidebarcommand');
+    let sidebarBroadcaster = document.getElementById(commandID);
+
+    sidebarBox.hidden = true;
+    sidebarSplitter.hidden = true;
+
+    sidebarEle.setAttribute('src', 'about:blank');
+    //sidebarEle.docShell.createAboutBlankContentViewer(null);
+
+    sidebarBroadcaster.removeAttribute('checked');
+    sidebarBox.setAttribute('sidebarcommand', '');
+    sidebarTitle.value = '';
+    sidebarBox.hidden = true;
+    sidebarSplitter.hidden = true;
+
+    // TODO: perhaps this isn't necessary if the window is not most recent?
+    window.gBrowser.selectedBrowser.focus();
+  }
+
+  return promise;
+}
+exports.hideSidebar = hideSidebar;
+
+function makeID(id) {
+  return 'jetpack-sidebar-' + id;
+}
diff --git a/toolkit/jetpack/sdk/ui/state.js b/toolkit/jetpack/sdk/ui/state.js
new file mode 100644
index 000000000..152ce696d
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/state.js
@@ -0,0 +1,239 @@
+/* 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/. */
+'use strict';
+
+// The Button module currently supports only Firefox.
+// See: https://bugzilla.mozilla.org/show_bug.cgi?id=jetpack-panel-apps
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '*',
+    'SeaMonkey': '*',
+    'Thunderbird': '*'
+  }
+};
+
+const { Ci } = require('chrome');
+
+const events = require('../event/utils');
+const { events: browserEvents } = require('../browser/events');
+const { events: tabEvents } = require('../tab/events');
+const { events: stateEvents } = require('./state/events');
+
+const { windows, isInteractive, getFocusedBrowser } = require('../window/utils');
+const { getActiveTab, getOwnerWindow } = require('../tabs/utils');
+
+const { ignoreWindow } = require('../private-browsing/utils');
+
+const { freeze } = Object;
+const { merge } = require('../util/object');
+const { on, off, emit } = require('../event/core');
+
+const { add, remove, has, clear, iterator } = require('../lang/weak-set');
+const { isNil } = require('../lang/type');
+
+const { viewFor } = require('../view/core');
+
+const components = new WeakMap();
+
+const ERR_UNREGISTERED = 'The state cannot be set or get. ' +
+  'The object may be not be registered, or may already have been unloaded.';
+
+const ERR_INVALID_TARGET = 'The state cannot be set or get for this target.' +
+  'Only window, tab and registered component are valid targets.';
+
+const isWindow = thing => thing instanceof Ci.nsIDOMWindow;
+const isTab = thing => thing.tagName && thing.tagName.toLowerCase() === 'tab';
+const isActiveTab = thing => isTab(thing) && thing === getActiveTab(getOwnerWindow(thing));
+const isEnumerable = window => !ignoreWindow(window);
+const browsers = _ =>
+  windows('navigator:browser', { includePrivate: true }).filter(isInteractive);
+const getMostRecentTab = _ => getActiveTab(getFocusedBrowser());
+
+function getStateFor(component, target) {
+  if (!isRegistered(component))
+    throw new Error(ERR_UNREGISTERED);
+
+  if (!components.has(component))
+    return null;
+
+  let states = components.get(component);
+
+  if (target) {
+    if (isTab(target) || isWindow(target) || target === component)
+      return states.get(target) || null;
+    else
+      throw new Error(ERR_INVALID_TARGET);
+  }
+
+  return null;
+}
+exports.getStateFor = getStateFor;
+
+function getDerivedStateFor(component, target) {
+  if (!isRegistered(component))
+    throw new Error(ERR_UNREGISTERED);
+
+  if (!components.has(component))
+    return null;
+
+  let states = components.get(component);
+
+  let componentState = states.get(component);
+  let windowState = null;
+  let tabState = null;
+
+  if (target) {
+    // has a target
+    if (isTab(target)) {
+      windowState = states.get(getOwnerWindow(target), null);
+
+      if (states.has(target)) {
+        // we have a tab state
+        tabState = states.get(target);
+      }
+    }
+    else if (isWindow(target) && states.has(target)) {
+      // we have a window state
+      windowState = states.get(target);
+    }
+  }
+
+  return freeze(merge({}, componentState, windowState, tabState));
+}
+exports.getDerivedStateFor = getDerivedStateFor;
+
+function setStateFor(component, target, state) {
+  if (!isRegistered(component))
+    throw new Error(ERR_UNREGISTERED);
+
+  let isComponentState = target === component;
+  let targetWindows = isWindow(target) ? [target] :
+                      isActiveTab(target) ? [getOwnerWindow(target)] :
+                      isComponentState ? browsers() :
+                      isTab(target) ? [] :
+                      null;
+
+  if (!targetWindows)
+    throw new Error(ERR_INVALID_TARGET);
+
+  // initialize the state's map
+  if (!components.has(component))
+    components.set(component, new WeakMap());
+
+  let states = components.get(component);
+
+  if (state === null && !isComponentState) // component state can't be deleted
+    states.delete(target);
+  else {
+    let base = isComponentState ? states.get(target) : null;
+    states.set(target, freeze(merge({}, base, state)));
+  }
+
+  render(component, targetWindows);
+}
+exports.setStateFor = setStateFor;
+
+function render(component, targetWindows) {
+  targetWindows = targetWindows ? [].concat(targetWindows) : browsers();
+
+  for (let window of targetWindows.filter(isEnumerable)) {
+    let tabState = getDerivedStateFor(component, getActiveTab(window));
+
+    emit(stateEvents, 'data', {
+      type: 'render',
+      target: component,
+      window: window,
+      state: tabState
+    });
+
+  }
+}
+exports.render = render;
+
+function properties(contract) {
+  let { rules } = contract;
+  let descriptor = Object.keys(rules).reduce(function(descriptor, name) {
+    descriptor[name] = {
+      get: function() { return getDerivedStateFor(this)[name] },
+      set: function(value) {
+        let changed = {};
+        changed[name] = value;
+
+        setStateFor(this, this, contract(changed));
+      }
+    }
+    return descriptor;
+  }, {});
+
+  return Object.create(Object.prototype, descriptor);
+}
+exports.properties = properties;
+
+function state(contract) {
+  return {
+    state: function state(target, state) {
+      let nativeTarget = target === 'window' ? getFocusedBrowser()
+                          : target === 'tab' ? getMostRecentTab()
+                          : target === this ? null
+                          : viewFor(target);
+
+      if (!nativeTarget && target !== this && !isNil(target))
+        throw new Error(ERR_INVALID_TARGET);
+
+      target = nativeTarget || target;
+
+      // jquery style
+      return arguments.length < 2
+        ? getDerivedStateFor(this, target)
+        : setStateFor(this, target, contract(state))
+    }
+  }
+}
+exports.state = state;
+
+const register = (component, state) => {
+  add(components, component);
+  setStateFor(component, component, state);
+}
+exports.register = register;
+
+const unregister = component => {
+  remove(components, component);
+}
+exports.unregister = unregister;
+
+const isRegistered = component => has(components, component);
+exports.isRegistered = isRegistered;
+
+var tabSelect = events.filter(tabEvents, e => e.type === 'TabSelect');
+var tabClose = events.filter(tabEvents, e => e.type === 'TabClose');
+var windowOpen = events.filter(browserEvents, e => e.type === 'load');
+var windowClose = events.filter(browserEvents, e => e.type === 'close');
+
+var close = events.merge([tabClose, windowClose]);
+var activate = events.merge([windowOpen, tabSelect]);
+
+on(activate, 'data', ({target}) => {
+  let [window, tab] = isWindow(target)
+                        ? [target, getActiveTab(target)]
+                        : [getOwnerWindow(target), target];
+
+  if (ignoreWindow(window)) return;
+
+  for (let component of iterator(components)) {
+    emit(stateEvents, 'data', {
+      type: 'render',
+      target: component,
+      window: window,
+      state: getDerivedStateFor(component, tab)
+    });
+  }
+});
+
+on(close, 'data', function({target}) {
+  for (let component of iterator(components)) {
+    components.get(component).delete(target);
+  }
+});
diff --git a/toolkit/jetpack/sdk/ui/state/events.js b/toolkit/jetpack/sdk/ui/state/events.js
new file mode 100644
index 000000000..98909656a
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/state/events.js
@@ -0,0 +1,18 @@
+/* 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/. */
+
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental',
+  'engines': {
+    'Firefox': '*',
+    'SeaMonkey': '*',
+    'Thunderbird': '*'
+  }
+};
+
+var channel = {};
+
+exports.events = channel;
diff --git a/toolkit/jetpack/sdk/ui/toolbar.js b/toolkit/jetpack/sdk/ui/toolbar.js
new file mode 100644
index 000000000..c1becab2d
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/toolbar.js
@@ -0,0 +1,16 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+const { Toolbar } = require("./toolbar/model");
+require("./toolbar/view");
+
+exports.Toolbar = Toolbar;
diff --git a/toolkit/jetpack/sdk/ui/toolbar/model.js b/toolkit/jetpack/sdk/ui/toolbar/model.js
new file mode 100644
index 000000000..5c5428606
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/toolbar/model.js
@@ -0,0 +1,151 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+const { Class } = require("../../core/heritage");
+const { EventTarget } = require("../../event/target");
+const { off, setListeners, emit } = require("../../event/core");
+const { Reactor, foldp, merges, send } = require("../../event/utils");
+const { Disposable } = require("../../core/disposable");
+const { InputPort } = require("../../input/system");
+const { OutputPort } = require("../../output/system");
+const { identify } = require("../id");
+const { pairs, object, map, each } = require("../../util/sequence");
+const { patch, diff } = require("diffpatcher/index");
+const { contract } = require("../../util/contract");
+const { id: addonID } = require("../../self");
+
+// Input state is accumulated from the input received form the toolbar
+// view code & local output. Merging local output reflects local state
+// changes without complete roundloop.
+const input = foldp(patch, {}, new InputPort({ id: "toolbar-changed" }));
+const output = new OutputPort({ id: "toolbar-change" });
+
+// Takes toolbar title and normalizes is to an
+// identifier, also prefixes with add-on id.
+const titleToId = title =>
+  ("toolbar-" + addonID + "-" + title).
+    toLowerCase().
+    replace(/\s/g, "-").
+    replace(/[^A-Za-z0-9_\-]/g, "");
+
+const validate = contract({
+  title: {
+    is: ["string"],
+    ok: x => x.length > 0,
+    msg: "The `option.title` string must be provided"
+  },
+  items: {
+    is:["undefined", "object", "array"],
+    msg: "The `options.items` must be iterable sequence of items"
+  },
+  hidden: {
+    is: ["boolean", "undefined"],
+    msg: "The `options.hidden` must be boolean"
+  }
+});
+
+// Toolbars is a mapping between `toolbar.id` & `toolbar` instances,
+// which is used to find intstance for dispatching events.
+var toolbars = new Map();
+
+const Toolbar = Class({
+  extends: EventTarget,
+  implements: [Disposable],
+  initialize: function(params={}) {
+    const options = validate(params);
+    const id = titleToId(options.title);
+
+    if (toolbars.has(id))
+      throw Error("Toolbar with this id already exists: " + id);
+
+    // Set of the items in the toolbar isn't mutable, as a matter of fact
+    // it just defines desired set of items, actual set is under users
+    // control. Conver test to an array and freeze to make sure users won't
+    // try mess with it.
+    const items = Object.freeze(options.items ? [...options.items] : []);
+
+    const initial = {
+      id: id,
+      title: options.title,
+      // By default toolbars are visible when add-on is installed, unless
+      // add-on authors decides it should be hidden. From that point on
+      // user is in control.
+      collapsed: !!options.hidden,
+      // In terms of state only identifiers of items matter.
+      items: items.map(identify)
+    };
+
+    this.id = id;
+    this.items = items;
+
+    toolbars.set(id, this);
+    setListeners(this, params);
+
+    // Send initial state to the host so it can reflect it
+    // into a user interface.
+    send(output, object([id, initial]));
+  },
+
+  get title() {
+    const state = reactor.value[this.id];
+    return state && state.title;
+  },
+  get hidden() {
+    const state = reactor.value[this.id];
+    return state && state.collapsed;
+  },
+
+  destroy: function() {
+    send(output, object([this.id, null]));
+  },
+  // `JSON.stringify` serializes objects based of the return
+  // value of this method. For convinienc we provide this method
+  // to serialize actual state data. Note: items will also be
+  // serialized so they should probably implement `toJSON`.
+  toJSON: function() {
+    return {
+      id: this.id,
+      title: this.title,
+      hidden: this.hidden,
+      items: this.items
+    };
+  }
+});
+exports.Toolbar = Toolbar;
+identify.define(Toolbar, toolbar => toolbar.id);
+
+const dispose = toolbar => {
+  toolbars.delete(toolbar.id);
+  emit(toolbar, "detach");
+  off(toolbar);
+};
+
+const reactor = new Reactor({
+  onStep: (present, past) => {
+    const delta = diff(past, present);
+
+    each(([id, update]) => {
+      const toolbar = toolbars.get(id);
+
+      // Remove
+      if (!update)
+        dispose(toolbar);
+      // Add
+      else if (!past[id])
+        emit(toolbar, "attach");
+      // Update
+      else
+        emit(toolbar, update.collapsed ? "hide" : "show", toolbar);
+    }, pairs(delta));
+  }
+});
+reactor.run(input);
diff --git a/toolkit/jetpack/sdk/ui/toolbar/view.js b/toolkit/jetpack/sdk/ui/toolbar/view.js
new file mode 100644
index 000000000..4ef0c3d46
--- /dev/null
+++ b/toolkit/jetpack/sdk/ui/toolbar/view.js
@@ -0,0 +1,248 @@
+/* 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/. */
+"use strict";
+
+module.metadata = {
+  "stability": "experimental",
+  "engines": {
+    "Firefox": "> 28"
+  }
+};
+
+const { Cu } = require("chrome");
+const { CustomizableUI } = Cu.import('resource:///modules/CustomizableUI.jsm', {});
+const { subscribe, send, Reactor, foldp, lift, merges } = require("../../event/utils");
+const { InputPort } = require("../../input/system");
+const { OutputPort } = require("../../output/system");
+const { Interactive } = require("../../input/browser");
+const { CustomizationInput } = require("../../input/customizable-ui");
+const { pairs, map, isEmpty, object,
+        each, keys, values } = require("../../util/sequence");
+const { curry, flip } = require("../../lang/functional");
+const { patch, diff } = require("diffpatcher/index");
+const prefs = require("../../preferences/service");
+const { getByOuterId } = require("../../window/utils");
+const { ignoreWindow } = require('../../private-browsing/utils');
+
+const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
+const PREF_ROOT = "extensions.sdk-toolbar-collapsed.";
+
+
+// There are two output ports one for publishing changes that occured
+// and the other for change requests. Later is synchronous and is only
+// consumed here. Note: it needs to be synchronous to avoid race conditions
+// when `collapsed` attribute changes are caused by user interaction and
+// toolbar is destroyed between the ticks.
+const output = new OutputPort({ id: "toolbar-changed" });
+const syncoutput = new OutputPort({ id: "toolbar-change", sync: true });
+
+// Merge disptached changes and recevied changes from models to keep state up to
+// date.
+const Toolbars = foldp(patch, {}, merges([new InputPort({ id: "toolbar-changed" }),
+                                          new InputPort({ id: "toolbar-change" })]));
+const State = lift((toolbars, windows, customizable) =>
+  ({windows: windows, toolbars: toolbars, customizable: customizable}),
+  Toolbars, Interactive, new CustomizationInput());
+
+// Shared event handler that makes `event.target.parent` collapsed.
+// Used as toolbar's close buttons click handler.
+const collapseToolbar = event => {
+  const toolbar = event.target.parentNode;
+  toolbar.collapsed = true;
+};
+
+const parseAttribute = x =>
+  x === "true" ? true :
+  x === "false" ? false :
+  x === "" ? null :
+  x;
+
+// Shared mutation observer that is used to observe `toolbar` node's
+// attribute mutations. Mutations are aggregated in the `delta` hash
+// and send to `ToolbarStateChanged` channel to let model know state
+// has changed.
+const attributesChanged = mutations => {
+  const delta = mutations.reduce((changes, {attributeName, target}) => {
+    const id = target.id;
+    const field = attributeName === "toolbarname" ? "title" : attributeName;
+    let change = changes[id] || (changes[id] = {});
+    change[field] = parseAttribute(target.getAttribute(attributeName));
+    return changes;
+  }, {});
+
+  // Calculate what are the updates from the current state and if there are
+  // any send them.
+  const updates = diff(reactor.value, patch(reactor.value, delta));
+
+  if (!isEmpty(pairs(updates))) {
+    // TODO: Consider sending sync to make sure that there won't be a new
+    // update doing a delete in the meantime.
+    send(syncoutput, updates);
+  }
+};
+
+
+// Utility function creates `toolbar` with a "close" button and returns
+// it back. In addition it set's up a listener and observer to communicate
+// state changes.
+const addView = curry((options, {document, window}) => {
+  if (ignoreWindow(window))
+    return;
+
+  let view = document.createElementNS(XUL_NS, "toolbar");
+  view.setAttribute("id", options.id);
+  view.setAttribute("collapsed", options.collapsed);
+  view.setAttribute("toolbarname", options.title);
+  view.setAttribute("pack", "end");
+  view.setAttribute("customizable", "false");
+  view.setAttribute("style", "padding: 2px 0; max-height: 40px;");
+  view.setAttribute("mode", "icons");
+  view.setAttribute("iconsize", "small");
+  view.setAttribute("context", "toolbar-context-menu");
+  view.setAttribute("class", "chromeclass-toolbar");
+
+  let label = document.createElementNS(XUL_NS, "label");
+  label.setAttribute("value", options.title);
+  label.setAttribute("collapsed", "true");
+  view.appendChild(label);
+
+  let closeButton = document.createElementNS(XUL_NS, "toolbarbutton");
+  closeButton.setAttribute("id", "close-" + options.id);
+  closeButton.setAttribute("class", "close-icon");
+  closeButton.setAttribute("customizable", false);
+  closeButton.addEventListener("command", collapseToolbar);
+
+  view.appendChild(closeButton);
+
+  // In order to have a close button not costumizable, aligned on the right,
+  // leaving the customizable capabilities of Australis, we need to create
+  // a toolbar inside a toolbar.
+  // This is should be a temporary hack, we should have a proper XBL for toolbar
+  // instead. See:
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=982005
+  let toolbar = document.createElementNS(XUL_NS, "toolbar");
+  toolbar.setAttribute("id", "inner-" + options.id);
+  toolbar.setAttribute("defaultset", options.items.join(","));
+  toolbar.setAttribute("customizable", "true");
+  toolbar.setAttribute("style", "-moz-appearance: none; overflow: hidden");
+  toolbar.setAttribute("mode", "icons");
+  toolbar.setAttribute("iconsize", "small");
+  toolbar.setAttribute("context", "toolbar-context-menu");
+  toolbar.setAttribute("flex", "1");
+
+  view.insertBefore(toolbar, closeButton);
+
+  const observer = new document.defaultView.MutationObserver(attributesChanged);
+  observer.observe(view, { attributes: true,
+                           attributeFilter: ["collapsed", "toolbarname"] });
+
+  const toolbox = document.getElementById("navigator-toolbox");
+  toolbox.appendChild(view);
+});
+const viewAdd = curry(flip(addView));
+
+const removeView = curry((id, {document}) => {
+  const view = document.getElementById(id);
+  if (view) view.remove();
+});
+
+const updateView = curry((id, {title, collapsed, isCustomizing}, {document}) => {
+  const view = document.getElementById(id);
+
+  if (!view)
+    return;
+
+  if (title)
+    view.setAttribute("toolbarname", title);
+
+  if (collapsed !== void(0))
+    view.setAttribute("collapsed", Boolean(collapsed));
+
+  if (isCustomizing !== void(0)) {
+    view.querySelector("label").collapsed = !isCustomizing;
+    view.querySelector("toolbar").style.visibility = isCustomizing
+                                                ? "hidden" : "visible";
+  }
+});
+
+const viewUpdate = curry(flip(updateView));
+
+// Utility function used to register toolbar into CustomizableUI.
+const registerToolbar = state => {
+  // If it's first additon register toolbar as customizableUI component.
+  CustomizableUI.registerArea("inner-" + state.id, {
+    type: CustomizableUI.TYPE_TOOLBAR,
+    legacy: true,
+    defaultPlacements: [...state.items]
+  });
+};
+// Utility function used to unregister toolbar from the CustomizableUI.
+const unregisterToolbar = CustomizableUI.unregisterArea;
+
+const reactor = new Reactor({
+  onStep: (present, past) => {
+    const delta = diff(past, present);
+
+    each(([id, update]) => {
+      // If update is `null` toolbar is removed, in such case
+      // we unregister toolbar and remove it from each window
+      // it was added to.
+      if (update === null) {
+        unregisterToolbar("inner-" + id);
+        each(removeView(id), values(past.windows));
+
+        send(output, object([id, null]));
+      }
+      else if (past.toolbars[id]) {
+        // If `collapsed` state for toolbar was updated, persist
+        // it for a future sessions.
+        if (update.collapsed !== void(0))
+          prefs.set(PREF_ROOT + id, update.collapsed);
+
+        // Reflect update in each window it was added to.
+        each(updateView(id, update), values(past.windows));
+
+        send(output, object([id, update]));
+      }
+      // Hack: Mutation observers are invoked async, which means that if
+      // client does `hide(toolbar)` & then `toolbar.destroy()` by the
+      // time we'll get update for `collapsed` toolbar will be removed.
+      // For now we check if `update.id` is present which will be undefined
+      // in such cases.
+      else if (update.id) {
+        // If it is a new toolbar we create initial state by overriding
+        // `collapsed` filed with value persisted in previous sessions.
+        const state = patch(update, {
+          collapsed: prefs.get(PREF_ROOT + id, update.collapsed),
+        });
+
+        // Register toolbar and add it each window known in the past
+        // (note that new windows if any will be handled in loop below).
+        registerToolbar(state);
+        each(addView(state), values(past.windows));
+
+        send(output, object([state.id, state]));
+      }
+    }, pairs(delta.toolbars));
+
+    // Add views to every window that was added.
+    each(window => {
+      if (window)
+        each(viewAdd(window), values(past.toolbars));
+    }, values(delta.windows));
+
+    each(([id, isCustomizing]) => {
+      each(viewUpdate(getByOuterId(id), {isCustomizing: !!isCustomizing}),
+        keys(present.toolbars));
+
+    }, pairs(delta.customizable))
+  },
+  onEnd: state => {
+    each(id => {
+      unregisterToolbar("inner-" + id);
+      each(removeView(id), values(state.windows));
+    }, keys(state.toolbars));
+  }
+});
+reactor.run(State);