Issue #1512 - Improve handling of multiple selections.

IsSelectionEditable should check whether the focus node and anchor node
aren't null before trying to use them.
This also changes the initialization of selections' aOutIndex to the
last range in the selection as a fallback in case we don't add a range
later (in AddItem) which could also end up with a null selection
otherwise if the additional selection nodes are removed.

2 files changed, 9 insertions, 3 deletions

diff --git a/editor/libeditor/HTMLEditor.cpp b/editor/libeditor/HTMLEditor.cpp
index 368f7a3e9..532da7a15 100644
--- a/editor/libeditor/HTMLEditor.cpp
+++ b/editor/libeditor/HTMLEditor.cpp
@@ -3344,12 +3344,18 @@ HTMLEditor::GetIsSelectionEditable(bool* aIsSelectionEditable)
   RefPtr<Selection> selection = GetSelection();
   NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
 
+  nsINode* anchorNode = selection->GetAnchorNode();
+  nsINode* focusNode = selection->GetFocusNode();
+  if (!anchorNode || !focusNode) {
+    return NS_ERROR_FAILURE;
+  }
+
   // Per the editing spec as of June 2012: we have to have a selection whose
   // start and end nodes are editable, and which share an ancestor editing
   // host.  (Bug 766387.)
   *aIsSelectionEditable = selection->RangeCount() &&
-                          selection->GetAnchorNode()->IsEditable() &&
-                          selection->GetFocusNode()->IsEditable();
+                          anchorNode->IsEditable() &&
+                          focusNode->IsEditable();
 
   if (*aIsSelectionEditable) {
     nsINode* commonAncestor =
diff --git a/layout/generic/nsSelection.cpp b/layout/generic/nsSelection.cpp
index f2959dc9d..5ccb2d8bf 100644
--- a/layout/generic/nsSelection.cpp
+++ b/layout/generic/nsSelection.cpp
@@ -3844,7 +3844,7 @@ Selection::AddItem(nsRange* aItem, int32_t* aOutIndex, bool aNoStartSelect)
 
   if (mUserInitiated) {
     AutoTArray<RefPtr<nsRange>, 4> rangesToAdd;
-    *aOutIndex = -1;
+    *aOutIndex = int32_t(mRanges.Length()) - 1;
 
     nsIDocument* doc = GetParentObject();
     bool selectEventsEnabled =