http://bugs.winehq.org/show_bug.cgi?id=30966
--- Comment #2 from Jordan jordan@jordanhenderson.com 2012-06-20 19:52:24 CDT --- Sorry, it was set to Windows XP. Setting to Windows Vista does not change anything. I changed the setting to windows 2008 and the problem seems to be slightly better behaved. It still happens however there seems to be fewer cases of it.
I think that in Firefox 13.0, they made a change in the rendering. I believe I saw it in the release notes. I believe I saw a note that mozilla would have direct rendering again for linux. even though this is a windows build, perhaps something in that region of their code was touched.