There are some unused methods for GTK+2 and gdk_cairo_region() to render the focus ring. gdk_cairo_region iterates the rectangles of the region to call cairo_rectangle, so we can easily replace it.
Created attachment 238771 [details] Patch
Comment on attachment 238771 [details] Patch Very nice.
Committed r174041: <http://trac.webkit.org/changeset/174041>