Bug 670058 Stop drag handling for selection when the dragging frame selection detaches presShell r=smaug

layout/generic/nsFrameSelection.h

@@ -378,6 +378,11 @@ public:
     return sDraggingFrameSelection;
   }
 
+  /**
+   * Call AbortDragForSelection() when we abort handling the drag as selecting.
+   */
+  void AbortDragForSelection();
+
   /**
     if we are in table cell selection mode. aka ctrl click in table cell
    */
@@ -616,7 +621,11 @@ public:
 
   nsIPresShell *GetShell()const  { return mShell; }
 
-  void DisconnectFromPresShell() { StopAutoScrollTimer(); mShell = nsnull; }
+  void DisconnectFromPresShell()
+  {
+    AbortDragForSelection();
+    mShell = nsnull;
+  }
 private:
   nsresult TakeFocus(nsIContent *aNewFocus,
                      PRUint32 aContentOffset,

layout/generic/nsSelection.cpp

@@ -1927,15 +1927,33 @@ nsFrameSelection::SetMouseDownState(PRBool aState)
   mMouseDownState = aState;
 
   if (mMouseDownState) {
+    if (sDraggingFrameSelection) {
+      sDraggingFrameSelection->AbortDragForSelection();
+    }
     sDraggingFrameSelection = this;
   } else {
-    sDraggingFrameSelection = nsnull;
+    if (sDraggingFrameSelection == this) {
+      sDraggingFrameSelection = nsnull;
+    }
     mDragSelectingCells = PR_FALSE;
     PostReason(nsISelectionListener::MOUSEUP_REASON);
     NotifySelectionListeners(nsISelectionController::SELECTION_NORMAL); //notify that reason is mouse up please.
   }
 }
 
+void
+nsFrameSelection::AbortDragForSelection()
+{
+  if (sDraggingFrameSelection == this) {
+    sDraggingFrameSelection = nsnull;
+    mMouseDownState = PR_FALSE;
+    mDragSelectingCells = PR_FALSE;
+    PostReason(nsISelectionListener::NO_REASON);
+    NotifySelectionListeners(nsISelectionController::SELECTION_NORMAL);
+  }
+  StopAutoScrollTimer();
+}
+
 nsISelection*
 nsFrameSelection::GetSelection(SelectionType aType) const
 {