From <rdar://problem/9000193>. Open Window with animated Flash or composited content (often http://cnn.com has animated Flash on the front page), make the Window wider than 2048 pixels and then scroll. Page tears and stutters. This is caused because in this case the root (non-composited) content is in a Tiled Layer which updates asynchronously, so different tiles are updated at different times.
Created attachment 89215 [details] Patch
Comment on attachment 89215 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=89215&action=review > Source/WebCore/platform/graphics/GraphicsLayer.h:263 > + bool allowTiledLayer() const { return m_allowTiledLayer; } > + virtual void setAllowTiledLayer(bool b) { m_allowTiledLayer = b; } Previous to this, knowledge of tiled layers was hidden in GraphicsLayerCA. I think these methods should be on GraphicsLayerCA, and LayerTreeHost should cast.
Committed r83653: <http://trac.webkit.org/changeset/83653>