on the whole group, so that the possible 'close?' dialog has a recent
timestamp even if the window about to be closed wasn't active.
svn path=/trunk/kdebase/kwin/; revision=291859
the startup notification property, but it could be extended
to read icons etc. as well if needed (ICCCM 4.1.2.7).
svn path=/trunk/kdebase/kwin/; revision=291218
