In r83820, an extra GraphicsLayer was added to the RenderLayerCompositor to contain all other layers, including the new scroll bar layers. The layer never gets a size set, since it's merely a container. This breaks PageClientQGraphicsWidget's assumption that the outermost layer should clip its children. This is already handled by the RenderLayerCompositor's "clip layer."
Created attachment 93651 [details] Proposed patch
Comment on attachment 93651 [details] Proposed patch Good find! :-)
Comment on attachment 93651 [details] Proposed patch Clearing flags on attachment: 93651 Committed r86582: <http://trac.webkit.org/changeset/86582>
All reviewed patches have been landed. Closing bug.
Is there a way to catch such regressions?
Revision r86582 cherry-picked into qtwebkit-2.2 with commit 816a9ab <http://gitorious.org/webkit/qtwebkit/commit/816a9ab>