When you hover over the model dropdowns along the top of http://progress.audiusa.com/, the contents of the dropdown jump when it displays. This doesn't happen if accelerated compositing is disabled.
<rdar://problem/9155330>
Created attachment 86184 [details] Screenshot
Created attachment 87055 [details] Testcase
Created attachment 88968 [details] Patch
Comment on attachment 88968 [details] Patch r=me
http://trac.webkit.org/changeset/83424