fix crash in winecfg's x11 dialog due to invalid "Desktop" settings

[Mike Hearn]

On Mon, 29 Mar 2004 10:11:56 -0500, chmorgan wrote:
> Yes, my bad.  I'll send in a fixed patch.  I still don't like the way the code 
> looks with the duplication of the default string to use but I couldn't
> think of any way to fix it more elegantly.  Ideas?

Why not just have  static char *desktop_default = "640x480" at the top of
the function?