http://bugs.winehq.org/show_bug.cgi?id=31493
--- Comment #9 from Henri Verbeet hverbeet@gmail.com 2012-10-17 06:31:04 CDT --- Allowing occlusion queries to be shared across contexts would require a GL extension. We have been considering some wined3d changes that would avoid the issue for some time now, but it's a non-trivial change, with questionable benefits.