contentEditable columns do not place the cursor in the right place This is undoubtably a bug in positionForCoordinates. Probably very easy to fix. Note that the focus ring drawing issue seen in this test is covered by bug 24136.
Created attachment 27936 [details] test case showing editing and columns not playing nice
Actually, this bug is more general. If you actually try to type, we don't repaint right either. I guess we could split that part out into a separate bug too.