--- a/gfx/layers/composite/LayerManagerComposite.cpp
+++ b/gfx/layers/composite/LayerManagerComposite.cpp
@@ -266,16 +266,19 @@ LayerManagerComposite::Render()
     return;
   }
 
   if (mComposer2D && mComposer2D->TryRender(mRoot, mWorldMatrix)) {
     mCompositor->EndFrameForExternalComposition(mWorldMatrix);
     return;
   }
 
+  
+  mCompositor->GetWidget()->PreRender(this);
+
   nsIntRect clipRect;
   Rect bounds(mRenderBounds.x, mRenderBounds.y, mRenderBounds.width, mRenderBounds.height);
   Rect actualBounds;
   if (mRoot->GetClipRect()) {
     clipRect = *mRoot->GetClipRect();
     WorldTransformRect(clipRect);
     Rect rect(clipRect.x, clipRect.y, clipRect.width, clipRect.height);
     mCompositor->BeginFrame(&rect, mWorldMatrix, bounds, nullptr, &actualBounds);

--- a/gfx/layers/opengl/CompositingRenderTargetOGL.h
+++ b/gfx/layers/opengl/CompositingRenderTargetOGL.h
@@ -110,16 +110,24 @@ public:
    */
   void BindRenderTarget()
   {
     if (mInitParams.mStatus != InitParams::INITIALIZED) {
       InitializeImpl();
     } else {
       MOZ_ASSERT(mInitParams.mStatus == InitParams::INITIALIZED);
       mGL->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mFBO);
+      GLenum result = mGL->fCheckFramebufferStatus(LOCAL_GL_FRAMEBUFFER);
+      if (result != LOCAL_GL_FRAMEBUFFER_COMPLETE) {
+        nsAutoCString msg;
+        msg.AppendPrintf("Framebuffer not complete -- error 0x%x, aFBOTextureTarget 0x%x, aRect.width %d, aRect.height %d",
+                         result, mInitParams.mFBOTextureTarget, mInitParams.mSize.width, mInitParams.mSize.height);
+        NS_WARNING(msg.get());
+      }
+
       mCompositor->PrepareViewport(mInitParams.mSize, mTransform);
     }
   }
 
   GLuint GetFBO() const
   {
     MOZ_ASSERT(mInitParams.mStatus == InitParams::INITIALIZED);
     return mFBO;

--- a/widget/cocoa/nsChildView.h
+++ b/widget/cocoa/nsChildView.h
@@ -319,16 +319,17 @@ typedef NSInteger NSEventGestureAxis;
 
 - (BOOL)isPluginView;
 
 // Are we processing an NSLeftMouseDown event that will fail to click through?
 // If so, we shouldn't focus or unfocus a plugin.
 - (BOOL)isInFailingLeftClickThrough;
 
 - (void)setGLContext:(NSOpenGLContext *)aGLContext;
+- (void)preRender:(NSOpenGLContext *)aGLContext;
 
 // Simple gestures support
 //
 // XXX - The swipeWithEvent, beginGestureWithEvent, magnifyWithEvent,
 // rotateWithEvent, and endGestureWithEvent methods are part of a
 // PRIVATE interface exported by nsResponder and reverse-engineering
 // was necessary to obtain the methods' prototypes. Thus, Apple may
 // change the interface in the future without notice.
@@ -512,16 +513,17 @@ public:
 #ifdef ACCESSIBILITY
   already_AddRefed<mozilla::a11y::Accessible> GetDocumentAccessible();
 #endif
 
   virtual void CreateCompositor();
   virtual gfxASurface* GetThebesSurface();
   virtual void PrepareWindowEffects() MOZ_OVERRIDE;
   virtual void CleanupWindowEffects() MOZ_OVERRIDE;
+  virtual void PreRender(LayerManager* aManager) MOZ_OVERRIDE;
   virtual void DrawWindowOverlay(LayerManager* aManager, nsIntRect aRect) MOZ_OVERRIDE;
 
   virtual void UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries);
 
   NS_IMETHOD BeginSecureKeyboardInput();
   NS_IMETHOD EndSecureKeyboardInput();
 
   void              HidePlugin();

--- a/widget/cocoa/nsChildView.mm
+++ b/widget/cocoa/nsChildView.mm
@@ -1865,16 +1865,24 @@ nsChildView::PrepareWindowEffects()
 void
 nsChildView::CleanupWindowEffects()
 {
   mResizerImage = nullptr;
   mCornerMaskImage = nullptr;
 }
 
 void
+nsChildView::PreRender(LayerManager* aManager)
+{
+  nsAutoPtr<GLManager> manager(GLManager::CreateGLManager(aManager));
+  NSOpenGLContext *glContext = (NSOpenGLContext *)manager->gl()->GetNativeData(GLContext::NativeGLContext);
+  [(ChildView*)mView preRender:glContext];
+}
+
+void
 nsChildView::DrawWindowOverlay(LayerManager* aManager, nsIntRect aRect)
 {
   nsAutoPtr<GLManager> manager(GLManager::CreateGLManager(aManager));
   if (!manager) {
     return;
   }
 
   MaybeDrawResizeIndicator(manager, aRect);
@@ -2301,16 +2309,30 @@ NSEvent* gLastDragMouseDownEvent = nil;
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
   mGLContext = aGLContext;
   [mGLContext retain];
 
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }
 
+-(void)preRender:(NSOpenGLContext *)aGLContext
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (!mGLContext) {
+    [self setGLContext:aGLContext];
+  }
+
+  [aGLContext setView:self];
+  [aGLContext update];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+
 - (void)dealloc
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
   [mGLContext release];
   [mPendingDirtyRects release];
   [mLastMouseDownEvent release];
   [mClickThroughMouseDownEvent release];

--- a/widget/nsIWidget.h
+++ b/widget/nsIWidget.h
@@ -87,18 +87,18 @@ typedef nsEventStatus (* EVENT_CALLBACK)
 #ifdef XP_WIN
 #define NS_NATIVE_TSF_THREAD_MGR       100
 #define NS_NATIVE_TSF_CATEGORY_MGR     101
 #define NS_NATIVE_TSF_DISPLAY_ATTR_MGR 102
 #define NS_NATIVE_ICOREWINDOW          103 // winrt specific
 #endif
 
 #define NS_IWIDGET_IID \
-{ 0x16da2e50, 0x0fee, 0x4719, \
-  { 0x93, 0x37, 0xce, 0xd4, 0xdd, 0xd2, 0x22, 0x53 } }
+{ 0x37b67cb4, 0x140c, 0x4d46, \
+  { 0xa9, 0xf8, 0x28, 0xcc, 0x08, 0x3d, 0x1f, 0x54 } }
 
 /*
  * Window shadow styles
  * Also used for the -moz-window-shadow CSS property
  */
 
 #define NS_STYLE_WINDOW_SHADOW_NONE             0
 #define NS_STYLE_WINDOW_SHADOW_DEFAULT          1
@@ -1164,16 +1164,18 @@ class nsIWidget : public nsISupports {
     /**
      * Called when shutting down the LayerManager to clean-up any cached resources.
      *
      * Always called from the compositing thread, which may be the main-thread if
      * OMTC is not enabled.
      */
     virtual void CleanupWindowEffects() = 0;
 
+    virtual void PreRender(LayerManager* aManager) = 0;
+
     /**
      * Called before the LayerManager draws the layer tree.
      *
      * Always called from the compositing thread, which may be the main-thread if
      * OMTC is not enabled.
      */
     virtual void DrawWindowUnderlay(LayerManager* aManager, nsIntRect aRect) = 0;
 

--- a/widget/xpwidgets/nsBaseWidget.h
+++ b/widget/xpwidgets/nsBaseWidget.h
@@ -113,16 +113,17 @@ public:
                                           LayerManagerPersistence aPersistence = LAYER_MANAGER_CURRENT,
                                           bool* aAllowRetaining = nullptr);
 
   virtual CompositorParent* NewCompositorParent(int aSurfaceWidth, int aSurfaceHeight);
   virtual void            CreateCompositor();
   virtual void            CreateCompositor(int aWidth, int aHeight);
   virtual void            PrepareWindowEffects() {}
   virtual void            CleanupWindowEffects() {}
+  virtual void            PreRender(LayerManager* aManager) {}
   virtual void            DrawWindowUnderlay(LayerManager* aManager, nsIntRect aRect) {}
   virtual void            DrawWindowOverlay(LayerManager* aManager, nsIntRect aRect) {}
   virtual void            UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) {}
   virtual gfxASurface*    GetThebesSurface();
   NS_IMETHOD              SetModal(bool aModal); 
   NS_IMETHOD              SetWindowClass(const nsAString& xulWinType);
   // Return whether this widget interprets parameters to Move and Resize APIs
   // as "global display pixels" rather than "device pixels", and therefore