Add support for NET_WM_STATE_FOCUSED

Bug: 11067

GTK3 applications (and client-side decorations in
particular) rely on NET_WM_STATE_FOCUSED property.

Signed-off-by: John Lindgren <john.lindgren@aol.com>
Signed-off-by: Olivier Fourdan <fourdan@xfce.org>
Silent a leftover degug message

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>