http://bugs.winehq.org/show_bug.cgi?id=22500
--- Comment #5 from Dan Kegel dank@kegel.com 2010-04-27 07:57:53 --- X must be bulletproof, or it's not worth the bits it's printed on. This bug is invalid for Wine, it must be fixed in X.
Now, if X doesn't crash, and Steam doesn't work because Wine does something stupid to X, that might be a Wine bug, but you'd need to file a separate bug for that.