I see it happen for compositing/geometry/clipping-foreground.html when I run all the tests on Windows with a debug build. CGContextRef GraphicsContext::platformContext() const { ASSERT(!paintingDisabled()); > WebKit.dll!WebCore::GraphicsContext::platformContext() Line 267 + 0x35 bytes C++ WebKit.dll!WebCore::MediaPlayerPrivateQuickTimeVisualContext::paint(WebCore::GraphicsContext * p=0x0030e7f8, const WebCore::IntRect & r={...}) Line 761 + 0x8 bytes C++ WebKit.dll!WebCore::MediaPlayer::paint(WebCore::GraphicsContext * p=0x0030e7f8, const WebCore::IntRect & r={...}) Line 719 + 0x28 bytes C++ WebKit.dll!WebCore::RenderVideo::paintReplaced(WebCore::PaintInfo & paintInfo={...}, const WebCore::FractionalLayoutPoint & paintOffset={...}) Line 224 C++ WebKit.dll!WebCore::RenderReplaced::paint(WebCore::PaintInfo & paintInfo={...}, const WebCore::FractionalLayoutPoint & paintOffset={...}) Line 153 + 0x1a bytes C++ WebKit.dll!WebCore::RenderImage::paint(WebCore::PaintInfo & paintInfo={...}, const WebCore::FractionalLayoutPoint & paintOffset={...}) Line 372 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContents(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & parentPaintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3092 + 0x34 bytes C++ WebKit.dll!WebCore::RenderLayer::paintLayerContentsAndReflection(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2965 C++ WebKit.dll!WebCore::RenderLayer::paintLayer(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2946 C++ WebKit.dll!WebCore::RenderLayer::paintList(WTF::Vector<WebCore::RenderLayer *,0> * list=[1](0x055360ec {m_inResizeMode=false m_scrollDimensionsDirty=true m_zOrderListsDirty=false ...}), WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3174 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContents(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & parentPaintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3115 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContentsAndReflection(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2965 C++ WebKit.dll!WebCore::RenderLayer::paintLayer(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2946 C++ WebKit.dll!WebCore::RenderLayer::paintList(WTF::Vector<WebCore::RenderLayer *,0> * list=[3](0x055362bc {m_inResizeMode=false m_scrollDimensionsDirty=false m_zOrderListsDirty=false ...},0x055363a4 {m_inResizeMode=false m_scrollDimensionsDirty=true m_zOrderListsDirty=false ...},0x05536914 {m_inResizeMode=false m_scrollDimensionsDirty=false m_zOrderListsDirty=false ...}), WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3174 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContents(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & parentPaintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3118 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContentsAndReflection(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2965 C++ WebKit.dll!WebCore::RenderLayer::paintLayer(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 2946 C++ WebKit.dll!WebCore::RenderLayer::paintList(WTF::Vector<WebCore::RenderLayer *,0> * list=[1](0x055361d4 {m_inResizeMode=false m_scrollDimensionsDirty=true m_zOrderListsDirty=false ...}), WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3174 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContents(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & parentPaintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=228) Line 3118 C++ WebKit.dll!WebCore::RenderLayer::paintLayerContentsAndReflection(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=4) Line 2965 C++ WebKit.dll!WebCore::RenderLayer::paintLayer(WebCore::RenderLayer * rootLayer=0x05535e34, WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & paintDirtyRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, WTF::HashMap<WebCore::OverlapTestRequestClient *,WebCore::IntRect,WTF::PtrHash<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::OverlapTestRequestClient *>,WTF::HashTraits<WebCore::IntRect> > * overlapTestRequests=0x0030e5bc, unsigned int paintFlags=4) Line 2946 C++ WebKit.dll!WebCore::RenderLayer::paint(WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::FractionalLayoutRect & damageRect={...}, unsigned int paintBehavior=0, WebCore::RenderObject * paintingRoot=0x00000000, WebCore::RenderRegion * region=0x00000000, unsigned int paintFlags=0) Line 2759 C++ WebKit.dll!WebCore::FrameView::paintContents(WebCore::GraphicsContext * p=0x0030e7f8, const WebCore::IntRect & rect={...}) Line 3101 C++ WebKit.dll!WebCore::ScrollView::paint(WebCore::GraphicsContext * context=0x0030e7f8, const WebCore::IntRect & rect={...}) Line 1074 + 0x1a bytes C++ WebKit.dll!WebCore::FrameView::paintControlTints() Line 3005 + 0x23 bytes C++ WebKit.dll!WebCore::FrameView::updateControlTints() Line 2993 C++ WebKit.dll!WebCore::FocusController::setActive(bool active=true) Line 668 C++ WebKit.dll!WebView::updateActiveState() Line 3405 C++ WebKit.dll!WebView::WebViewWndProc(HWND__ * hWnd=0x002206e8, unsigned int message=275, unsigned int wParam=1, long lParam=0) Line 2388 C++ user32.dll!_InternalCallWinProc@20() + 0x23 bytes user32.dll!_UserCallWinProcCheckWow@32() + 0xd3 bytes user32.dll!_CallWindowProcAorW@24() + 0x5e bytes user32.dll!_CallWindowProcW@20() + 0x1b bytes comctl32.dll!_CallOriginalWndProc@24() + 0x1a bytes comctl32.dll!_CallNextSubclassProc@20() + 0x3d bytes comctl32.dll!_DefSubclassProc@16() + 0x46 bytes comctl32.dll!TTSubclassProc() + 0x3c bytes comctl32.dll!_CallNextSubclassProc@20() + 0x3d bytes comctl32.dll!_MasterSubclassProc@16() + 0x44 bytes user32.dll!_InternalCallWinProc@20() + 0x23 bytes user32.dll!_UserCallWinProcCheckWow@32() + 0xd3 bytes user32.dll!_DispatchMessageWorker@8() + 0xee bytes user32.dll!_DispatchMessageW@4() + 0xf bytes DumpRenderTree.dll!runTest(const std::basic_string<char,std::char_traits<char>,std::allocator<char> > & testPathOrURL="H:\home\jhoneycutt\src\OpenSource\LayoutTests\compositing\geometry\clipping-foreground.html") Line 1049 + 0xf bytes C++ DumpRenderTree.dll!dllLauncherEntryPoint(int argc=2, const char * * argv=0x01196f58) Line 1431 + 0x28 bytes C++ DumpRenderTree.exe!main(int argc=2, const char * * argv=0x01196f58) Line 198 + 0x10 bytes C++ DumpRenderTree.exe!__tmainCRTStartup() Line 597 + 0x17 bytes C kernel32.dll!@BaseThreadInitThunk@12() + 0xe bytes ntdll.dll!___RtlUserThreadStart@8() + 0x23 bytes ntdll.dll!__RtlUserThreadStart@8() + 0x1b bytes I will skip for now it to get the bots greener. Possibly related to https://bugs.webkit.org/show_bug.cgi?id=88149
<rdar://problem/11579549>