This is going to be a controversal change. It enforces KWin decorations
on all client side decorated windows from GTK+. Unfortunately we are
caught between a rock and a hard place. Keeping the status quo means
having broken windows and a more or less broken window manager due to
GTK+ including the shadow in the windows. This is no solution.
Enforcing server side decorations visually breaks the windows. This is
also no solution. So why do it?

It's our task to provide the best possible user experience and KWin is
a window manager which has always done great efforts to fix misbehaving
windows. One can think of the focus stealing prevention, the window rules
and lately the scripts. The best possible window management experience is
our aim. This means we cannot leave the users with the broken windows
from GTK.

The issues we noticed were reported to GTK+ about 2 months ago and we are
working on improving the situation. Unfortunately several issues are...