Created attachment 39647 [details] Patch v1 If a WebView and an adjacent sibling window have their positions changed on screen at the same time, in some cases the WebView will end up painting over the sibling window.
https://bugs.webkit.org/show_bug.cgi?id=29300
<rdar://problem/7227960>
I'd love to get Steve's opinion on whether there's a reason we haven't been using WS_CLIPSIBLINGS before now.
Committed r48439: <http://trac.webkit.org/changeset/48439>