diff --git a/modules/plugin/base/src/nsPluginNativeWindowOS2.cpp b/modules/plugin/base/src/nsPluginNativeWindowOS2.cpp
index 9f70587695ec..6c3a7c4101fc 100644
--- a/modules/plugin/base/src/nsPluginNativeWindowOS2.cpp
+++ b/modules/plugin/base/src/nsPluginNativeWindowOS2.cpp
@@ -308,14 +308,19 @@ static MRESULT EXPENTRY PluginWndProc(HWND hWnd, ULONG msg, MPARAM mp1, MPARAM m
       // doesn't receive it, window activation/deactivation won't happen.
       WinDefWindowProc(hWnd, msg, mp1, mp2);
 
-      // If focus is being gained, and the plugin widget neither lost
-      // nor gained the focus, then a child just got it from some other
-      // window.  Post a WM_FOCUSCHANGED msg that identifies the child
-      // as the window losing focus.  After nsWindow::ActivatePlugin()
-      // activates the plugin, it will restore the focus to the child.
+      // If focus is being gained, and the plugin widget neither lost nor
+      // gained the focus, then a child just got it from some other window.
+      // If that other window was neither a child of the widget nor owned
+      // by a child of the widget (e.g. a popup menu), post a WM_FOCUSCHANGED
+      // msg that identifies the child as the window losing focus.  After
+      // nsWindow:: ActivatePlugin() activates the plugin, it will restore
+      // the focus to the child.
       if (SHORT1FROMMP(mp2) && (HWND)mp1 != hWnd) {
         HWND hFocus = WinQueryFocus(HWND_DESKTOP);
-        if (hFocus != hWnd) {
+        if (hFocus != hWnd &&
+            WinIsChild(hFocus, hWnd) &&
+            !WinIsChild((HWND)mp1, hWnd) &&
+            !WinIsChild(WinQueryWindow((HWND)mp1, QW_OWNER), hWnd)) {
           WinPostMsg(hWnd, WM_FOCUSCHANGED, (MPARAM)hFocus, mp2);
         }
       }
diff --git a/widget/src/os2/nsWindow.cpp b/widget/src/os2/nsWindow.cpp
index 6c67c11b9867..c46d52defa68 100644
--- a/widget/src/os2/nsWindow.cpp
+++ b/widget/src/os2/nsWindow.cpp
@@ -261,6 +261,13 @@ nsWindow::~nsWindow()
     Destroy();
   }
 
+  // Once a plugin window has been destroyed,
+  // its parent, the clipping window, can be destroyed.
+  if (mClipWnd) {
+    WinDestroyWindow(mClipWnd);
+    mClipWnd = 0;
+  }
+ 
   // If it exists, destroy our os2FrameWindow helper object.
   if (mFrame) {
     delete mFrame;
@@ -812,11 +819,11 @@ void nsWindow::Scroll(const nsIntPoint& aDelta,
         // but not the part outside it [at least on Windows].  For
         // these widgets, we have to invalidate them to get both
         // parts updated after the scroll.
-        if (w->mBounds.Intersects(affectedRect)) {
+        if (w->mWnd && w->mBounds.Intersects(affectedRect)) {
           if (!ClipRegionContainedInRect(configuration.mClipRegion,
-                                         affectedRect - (w->mBounds.TopLeft()
-                                                         + aDelta)) && mWnd) {
-            WinInvalidateRect(mWnd, 0, FALSE);
+                                         affectedRect - 
+                                         (w->mBounds.TopLeft() + aDelta))) {
+            WinInvalidateRect(w->mWnd, 0, FALSE);
           }
 
           // Send a WM_VRNDISABLED to the plugin child of this widget.