The X server sends several RRScreenChangeNotify events in a burst when
something happens which, currently, causes us to rebuild our view of
the world as many times and notify the upper layers about it which
causes a lot of bogus repeated work like rebuilding background actors.
We can avoid this extra work by looking at the timestamp in the
XRRScreenResources struct which is updated when an X client (including
us!) last changed something and comparing it with the previous
timestamp.
https://bugzilla.gnome.org/show_bug.cgi?id=738630
47e339b46e