http://bugs.winehq.org/show_bug.cgi?id=15141
--- Comment #4 from Dan Hipschman dsh@linux.ucla.edu 2008-09-08 12:36:23 --- Yea, --single-process is a workaround. It's because when it says "X11DRV_SetWindowRgn not supported on other thread," the thread is in another process.