http://bugs.winehq.org/show_bug.cgi?id=21708
--- Comment #42 from Rafał Mużyło galtgendo@o2.pl 2013-05-26 21:51:50 CDT --- Well, the patch works, so it looks as before it, wine can create a situation where device->contexts[0]->glCtx exists, but device->context_count is zero.
Well, at least that's my guess, that the patch was based upon, before it tested positively.
Perhaps one of the functions isn't initializing all of the fields ?