http://bugs.winehq.org/show_bug.cgi?id=14045
--- Comment #11 from Roderick Colenbrander thunderbird2k@gmx.net 2008-08-14 16:24:53 --- We haven't had apps that required software rendering. Sketchup used to work but I'm not sure when it stopped working. Perhaps it was after we unleashed all the pixel formats (we used to have only 1 due to some x11drv limitations). Try a regression test.
It must be some generic fall back, there must also be some format which it really wants to have. I doubt it wants to use software rendering.