diff --git a/mozilla/widget/src/gtk/nsWindow.cpp b/mozilla/widget/src/gtk/nsWindow.cpp
index f8e7e740a58..7197471225b 100644
--- a/mozilla/widget/src/gtk/nsWindow.cpp
+++ b/mozilla/widget/src/gtk/nsWindow.cpp
@@ -204,6 +204,9 @@ static void printDepth(int depth) {
 }
 #endif
 
+static int is_parent_ungrab_enter(GdkEventCrossing *aEvent);
+static int is_parent_grab_leave(GdkEventCrossing *aEvent);
+
 
 // This function will check if a button event falls inside of a
 // window's bounds.
@@ -1752,6 +1755,7 @@ nsWindow::InstallFocusOutSignal(GtkWidget * aWidget)
 				GTK_SIGNAL_FUNC(nsWindow::FocusOutSignal));
 }
 
+
 void 
 nsWindow::HandleGDKEvent(GdkEvent *event)
 {
@@ -1775,9 +1779,15 @@ nsWindow::HandleGDKEvent(GdkEvent *event)
     OnButtonReleaseSignal (&event->button);
     break;
   case GDK_ENTER_NOTIFY:
+    if(is_parent_ungrab_enter(&event->crossing))
+      return;
+
     OnEnterNotifySignal (&event->crossing);
     break;
   case GDK_LEAVE_NOTIFY:
+    if(is_parent_grab_leave(&event->crossing))
+      return;
+
     OnLeaveNotifySignal (&event->crossing);
     break;
 
@@ -4529,3 +4539,21 @@ nsWindow::ClearIconEntry(PLDHashTable* aTable, PLDHashEntryHdr* aHdr)
     free((void*) entry->string);
   PL_DHashClearEntryStub(aTable, aHdr);
 }
+
+/* static */
+int
+is_parent_ungrab_enter(GdkEventCrossing *event)
+{
+  return (GDK_CROSSING_UNGRAB == event->mode) &&
+    ((GDK_NOTIFY_ANCESTOR == event->detail) ||
+     (GDK_NOTIFY_VIRTUAL == event->detail));
+}
+
+/* static */
+int
+is_parent_grab_leave(GdkEventCrossing *event)
+{
+  return (GDK_CROSSING_GRAB == event->mode) &&
+    ((GDK_NOTIFY_ANCESTOR == event->detail) ||
+     (GDK_NOTIFY_VIRTUAL == event->detail));
+}
diff --git a/mozilla/widget/src/xlib/nsAppShell.cpp b/mozilla/widget/src/xlib/nsAppShell.cpp
index 45b134617c6..083080d696e 100644
--- a/mozilla/widget/src/xlib/nsAppShell.cpp
+++ b/mozilla/widget/src/xlib/nsAppShell.cpp
@@ -1047,6 +1047,23 @@ nsAppShell::HandleFocusOutEvent(XEvent *event, nsWidget *aWidget)
   NS_RELEASE(aWidget);
 }
 
+/* Identify pointer grab/ungrab events due to window manager activity */
+static inline int
+is_wm_ungrab_enter(XCrossingEvent *event)
+{
+  return (NotifyGrab == event->mode) &&
+    ((NotifyAncestor == event->detail) ||
+     (NotifyVirtual == event->detail));
+}
+
+static inline int
+is_wm_grab_leave(XCrossingEvent *event)
+{
+  return (NotifyGrab == event->mode) &&
+    ((NotifyAncestor == event->detail) ||
+     (NotifyVirtual == event->detail));
+}
+
 void
 nsAppShell::HandleEnterEvent(XEvent *event, nsWidget *aWidget)
 {
@@ -1054,6 +1071,9 @@ nsAppShell::HandleEnterEvent(XEvent *event, nsWidget *aWidget)
                                        event->xcrossing.window));
   nsMouseEvent enterEvent;
 
+  if(is_wm_ungrab_enter(&event->xcrossing))
+    return;
+
   if (mDragging) {
     HandleDragEnterEvent(event, aWidget);
   }
@@ -1084,6 +1104,9 @@ nsAppShell::HandleLeaveEvent(XEvent *event, nsWidget *aWidget)
 
   nsMouseEvent leaveEvent;
   
+  if(is_wm_grab_leave(&event->xcrossing))
+    return;
+
   if (mDragging) {
     HandleDragLeaveEvent(event, aWidget);
   }