http://bugs.winehq.org/show_bug.cgi?id=24308
--- Comment #6 from Georg Hennig georg298@gmx.de 2010-11-09 06:09:40 CST --- This fullscreen mode actually is supported in my xorg conf file, therefore fullscreen mode works with the patch above at this resolution 800x600.
If I remember well, this error just means "800x600 does not exist at this refresh rate, so wine's falling back to 800x600 at any refresh rate", which works fine.