From 33c856dd7117df4cf8a272f2c896ba1760afdc3c Mon Sep 17 00:00:00 2001
From: Fedor <fedor@mail.ru>
Date: Thu, 7 May 2020 14:45:29 +0300
Subject: [PATCH] Improve handling of multiple selections.

---
 editor/libeditor/HTMLEditor.cpp | 10 ++++++++--
 layout/generic/nsSelection.cpp  |  2 +-
 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 =