Bug 596600 - Start generating window-level mouse out events at the root EventStateManager. r=smaug

layout/base/nsPresShell.cpp

@@ -6722,10 +6722,15 @@ PresShell::HandleEvent(nsIView         *aView,
       }
     }
 
+    PRBool isWindowLevelMouseExit = (aEvent->message == NS_MOUSE_EXIT) &&
+      (static_cast<nsMouseEvent*>(aEvent)->exit == nsMouseEvent::eTopLevel);
+
     // Get the frame at the event point. However, don't do this if we're
     // capturing and retargeting the event because the captured frame will
-    // be used instead below.
-    if (!captureRetarget) {
+    // be used instead below. Also keep using the root frame if we're dealing
+    // with a window-level mouse exit event since we want to start sending
+    // mouse out events at the root EventStateManager.
+    if (!captureRetarget && !isWindowLevelMouseExit) {
       nsPoint eventPoint
           = nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, frame);
       {