WM_GETICON patch

[Chris]

Here's a patch I'm trying to make to implement the WM_GETICON message, which 
programs like GeoShell (a Win32 taskbar replacement) would use to get a 
taskbar icon for the running processes. I'm not quite sure if it's proper or 
not, though. Originally GeoShell would show no icon on the taskbar and print 
a lot of fixme messages about it being unsupported. With this patch it now 
(always) shows the Wine glass icon for programs, with no such fixme messages. 
Since I'm unable to try it on a real Windows machine, I don't know if it's 
the right behavior for it to always show the generic icon like that.

Feedback and help would be appreciated.