--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -378,17 +378,21 @@ public:
   void* SetPluginPortAndDetectChange();
   // Flag when we've set up a Thebes (and CoreGraphics) context in
   // nsObjectFrame::PaintPlugin().  We need to know this in
   // FixUpPluginWindow() (i.e. we need to know when FixUpPluginWindow() has
   // been called from nsObjectFrame::PaintPlugin() when we're using the
   // CoreGraphics drawing model).
   void BeginCGPaint();
   void EndCGPaint();
-#endif
+#else // XP_MACOSX
+  void UpdateWindowClipRect(PRBool aSetWindow);
+  void SetWindow();
+  void UpdateWindowVisibility(PRBool aVisible);
+#endif // XP_MACOSX
 
   void SetOwner(nsObjectFrame *aOwner)
   {
     mObjectFrame = aOwner;
   }
 
   PRUint32 GetLastEventloopNestingLevel() const {
     return mLastEventloopNestingLevel; 
@@ -509,16 +513,17 @@ private:
   PRPackedBool                mWidgetVisible;    // used on Mac to store our widget's visible state
 #ifdef XP_MACOSX
   PRPackedBool                mPluginPortChanged;
 #endif
 #ifdef MOZ_X11
   // Used with windowless plugins only, initialized in CreateWidget().
   PRPackedBool                mFlash10Quirks;
 #endif
+  PRPackedBool                mPluginWindowVisible;
 
   // If true, destroy the widget on destruction. Used when plugin stop
   // is being delayed to a safer point in time.
   PRPackedBool                mDestroyWidget;
   PRUint16          mNumCachedAttrs;
   PRUint16          mNumCachedParams;
   char              **mCachedAttrParamNames;
   char              **mCachedAttrParamValues;
@@ -823,16 +828,20 @@ nsObjectFrame::CreateWidget(nscoord aWid
       return NS_ERROR_FAILURE;
     pluginWidget->SetPluginEventModel(mInstanceOwner->GetEventModel());
     pluginWidget->SetPluginDrawingModel(mInstanceOwner->GetDrawingModel());
 
     if (mInstanceOwner->GetDrawingModel() == NPDrawingModelCoreAnimation) {
       mInstanceOwner->SetupCARefresh();
     }
 #endif
+  } else {
+#ifndef XP_MACOSX
+    rpc->RegisterPluginForGeometryUpdates(this);
+#endif
   }
 
   if (!IsHidden()) {
     viewMan->SetViewVisibility(view, nsViewVisibility_kShow);
   }
 
   return NS_OK;
 }
@@ -1063,25 +1072,25 @@ nsObjectFrame::FixupWindow(const nsSize&
   window->y = origin.y;
 
   window->width = presContext->AppUnitsToDevPixels(aSize.width);
   window->height = presContext->AppUnitsToDevPixels(aSize.height);
 
   // on the Mac we need to set the clipRect to { 0, 0, 0, 0 } for now. This will keep
   // us from drawing on screen until the widget is properly positioned, which will not
   // happen until we have finished the reflow process.
+#ifdef XP_MACOSX
   window->clipRect.top = 0;
   window->clipRect.left = 0;
-#ifdef XP_MACOSX
   window->clipRect.bottom = 0;
   window->clipRect.right = 0;
 #else
-  window->clipRect.bottom = presContext->AppUnitsToDevPixels(aSize.height);
-  window->clipRect.right = presContext->AppUnitsToDevPixels(aSize.width);
+  mInstanceOwner->UpdateWindowClipRect(PR_FALSE);
 #endif
+
   NotifyPluginReflowObservers();
 }
 
 void
 nsObjectFrame::CallSetWindow()
 {
   NPWindow *win = nsnull;
  
@@ -1097,18 +1106,16 @@ nsObjectFrame::CallSetWindow()
   nsPluginNativeWindow *window = (nsPluginNativeWindow *)win;
 #ifdef XP_MACOSX
   mInstanceOwner->FixUpPluginWindow(ePluginPaintDisable);
 #endif
 
   if (IsHidden())
     return;
 
-  PRBool windowless = (window->type == NPWindowTypeDrawable);
-
   // refresh the plugin port as well
   window->window = mInstanceOwner->GetPluginPortFromWidget();
 
   // Adjust plugin dimensions according to pixel snap results
   // and reduce amount of SetWindow calls
   nsPresContext* presContext = PresContext();
   nsRootPresContext* rootPC = presContext->GetRootPresContext();
   if (!rootPC)
@@ -1287,18 +1294,24 @@ nsDisplayPlugin::GetWidgetConfiguration(
   f->ComputeWidgetGeometry(mVisibleRegion, pluginOrigin, aConfigurations);
 }
 
 void
 nsObjectFrame::ComputeWidgetGeometry(const nsRegion& aRegion,
                                      const nsPoint& aPluginOrigin,
                                      nsTArray<nsIWidget::Configuration>* aConfigurations)
 {
-  if (!mWidget)
+  if (!mWidget) {
+#ifndef XP_MACOSX
+    if (mInstanceOwner) {
+      mInstanceOwner->UpdateWindowVisibility(!aRegion.IsEmpty());
+    }
+#endif
     return;
+  }
 
   nsPresContext* presContext = PresContext();
   nsRootPresContext* rootPC = presContext->GetRootPresContext();
   if (!rootPC)
     return;
 
   nsIWidget::Configuration* configuration = aConfigurations->AppendElement();
   if (!configuration)
@@ -2537,35 +2550,38 @@ nsObjectFrame::StopPlugin()
 
 void
 nsObjectFrame::StopPluginInternal(PRBool aDelayedStop)
 {
   if (!mInstanceOwner) {
     return;
   }
 
-  if (mWidget) {
-    nsRootPresContext* rootPC = PresContext()->GetRootPresContext();
-    if (rootPC) {
-      rootPC->UnregisterPluginForGeometryUpdates(this);
-
-      // Make sure the plugin is hidden in case an update of plugin geometry
-      // hasn't happened since this plugin became hidden.
-      nsIWidget* parent = mWidget->GetParent();
-      if (parent) {
-        nsTArray<nsIWidget::Configuration> configurations;
-        GetEmptyClipConfiguration(&configurations);
-        parent->ConfigureChildren(configurations);
-        DidSetWidgetGeometry();
-      }
+  nsRootPresContext* rpc = PresContext()->GetRootPresContext();
+  if (!rpc) {
+    NS_ASSERTION(PresContext()->PresShell()->IsFrozen(),
+                 "unable to unregister the plugin frame");
+  }
+  else if (mWidget) {
+    rpc->UnregisterPluginForGeometryUpdates(this);
+
+    // Make sure the plugin is hidden in case an update of plugin geometry
+    // hasn't happened since this plugin became hidden.
+    nsIWidget* parent = mWidget->GetParent();
+    if (parent) {
+      nsTArray<nsIWidget::Configuration> configurations;
+      GetEmptyClipConfiguration(&configurations);
+      parent->ConfigureChildren(configurations);
+      DidSetWidgetGeometry();
     }
-    else {
-      NS_ASSERTION(PresContext()->PresShell()->IsFrozen(),
-                   "unable to unregister the plugin frame");
-    }
+  }
+  else {
+#ifndef XP_MACOSX
+    rpc->UnregisterPluginForGeometryUpdates(this);
+#endif
   }
 
   // Transfer the reference to the instance owner onto the stack so
   // that if we do end up re-entering this code, or if we unwind back
   // here witha deleted frame (this), we can still continue to stop
   // the plugin. Note that due to that, the ordering of the code in
   // this function is extremely important.
 
@@ -2791,16 +2807,17 @@ nsPluginInstanceOwner::nsPluginInstanceO
 #endif
   mInCGPaintLevel = 0;
   mSentInitialTopLevelWindowEvent = PR_FALSE;
   mIOSurface = nsnull;
   mPluginPortChanged = PR_FALSE;
 #endif
   mContentFocused = PR_FALSE;
   mWidgetVisible = PR_TRUE;
+  mPluginWindowVisible = PR_FALSE;
   mNumCachedAttrs = 0;
   mNumCachedParams = 0;
   mCachedAttrParamNames = nsnull;
   mCachedAttrParamValues = nsnull;
   mDestroyWidget = PR_FALSE;
 
 #ifdef MOZ_COMPOSITED_PLUGINS
   mLastPoint = nsIntPoint(0,0);
@@ -6427,16 +6444,72 @@ void* nsPluginInstanceOwner::FixUpPlugin
 #ifdef MAC_CARBON_PLUGINS
   if (drawingModel == NPDrawingModelCoreGraphics && eventModel == NPEventModelCarbon)
     return static_cast<NP_CGContext*>(pluginPort)->window;
 #endif
 
   return nsnull;
 }
 
+#else // XP_MACOSX
+void nsPluginInstanceOwner::UpdateWindowClipRect(PRBool aSetWindow)
+{
+  if (!mPluginWindow)
+    return;
+
+  // For windowless plugins a non-empty clip rectangle will be
+  // passed to the plugin during paint, an additional update
+  // of the the clip rectangle here is not required
+  if (aSetWindow && !mWidget && mPluginWindowVisible)
+    return;
+
+  const NPRect oldClipRect = mPluginWindow->clipRect;
+
+  mPluginWindow->clipRect.left = 0;
+  mPluginWindow->clipRect.top = 0;
+
+  if (mPluginWindowVisible) {
+    mPluginWindow->clipRect.right = mPluginWindow->width;
+    mPluginWindow->clipRect.bottom = mPluginWindow->height;
+  } else {
+    mPluginWindow->clipRect.right = 0;
+    mPluginWindow->clipRect.bottom = 0;
+  }
+
+  if (!aSetWindow)
+    return;
+
+  if ((mPluginWindow->clipRect.left   != oldClipRect.left   ||
+       mPluginWindow->clipRect.top    != oldClipRect.top    ||
+       mPluginWindow->clipRect.right  != oldClipRect.right  ||
+       mPluginWindow->clipRect.bottom != oldClipRect.bottom)) {
+    SetWindow();
+  }
+}
+
+void
+nsPluginInstanceOwner::SetWindow()
+{
+  if (!mInstance)
+    return;
+
+  if (UseLayers()) {
+    mInstance->AsyncSetWindow(mPluginWindow);
+  } else {
+    mInstance->SetWindow(mPluginWindow);
+  }
+}
+
+void
+nsPluginInstanceOwner::UpdateWindowVisibility(PRBool aVisible)
+{
+  mPluginWindowVisible = aVisible;
+  UpdateWindowClipRect(PR_TRUE);
+}
+
 #endif // XP_MACOSX
 
 // Little helper function to resolve relative URL in
 // |value| for certain inputs of |name|
 void nsPluginInstanceOwner::FixUpURLS(const nsString &name, nsAString &value)
 {
   if (name.LowerCaseEqualsLiteral("pluginurl") ||
       name.LowerCaseEqualsLiteral("pluginspage")) {