[Patch] Minimize utility windows when all other group windows are minimized

[Hongli Lai <h lai chello nl>]

In Gimp, I can set the docks to become utility windows. Unfortunately, 
Metacity doesn't allow me to minimize utility windows, so the Gimp docks 
stay visible no matter what. I think utility windows should be minimized 
when all other windows in the application are minimized too. After all: 
utility windows are almost useless without the main window.

A patch can be found in Bugzilla:
http://bugs.gnome.org/show_bug.cgi?id=159359