F16 - Crashtastic

[John Wendel]

My F16 - Gnome box has developed an ugly bug today with the latest 
updates (from updates-testing).

Randomly, but very frequently, when I close a window, the windowing 
system hangs. I can move the mouse, and ctrl-alt-bksp works to kill X 
and restart GDM. Nothing interesting in the X log file. All other window 
actions like minimize and maximize work fine.

I'd like to report a bug, but I'm not sure where to point the finger.  
Can someone suggest a method of identifying the buggy program so I can 
report it?

Thanks,

John