Created attachment 39152 [details] testcase for the bug (might be simplified even further but I failed) When using a simple CSS "a:hover span" tooltip combined (possibly) with changes to the a, webkit creates artifacts (does not clean the image after hover ends). You have to scroll completely away and return for webkit to fix this. I have tried to isolate the case in the attachment. Also, I tested only on Windows X but this could be affecting all platforms.