Switch code to use gdk_display_is_composited() instead.
The new code also doesn't use a vfunc to query the property but rather
requires the backend to call set_composited()/set_rgba() to change the
value.
Also add properties for those two properties.
The first property is equivalent to checking if an RGBA visual exists,
the 2nd is equivalent to gdk_screen_is_composited().
These complicate a lot of GdkWindow internals to implement features
that not a lot of apps use, and will be better achieved using gsk.
So, we just drop it all.
This is an attempt to get rid of gdk_window_new() for more specific use
cases. These 2 are for client-side windows - regular ones and input-only
ones resepectively.
So far all those functions just call into gdk_window_new().
The update tracking code was ugly and using deprecated drawing APIs. It
was also in the wrong place.
So instead of trying to keep it working, I'll remove it. We need to find
a better way to put it and make it work there.
... and gdk_screen_get_window_stack().
Those functions were originally added in
5afb4f0f11 but do not seem to be used as
they are not implemented anywhere but in X.
As GDK is not meant to fulfill window management functionality I'm going
to remove these functions without replacements.
... and gdk_screen_get_width_mm() and gdk_screen_get_height_mm() and
the shortcut counterparts that call these functions on the default
screen.
Modern display servers don't provide an ability to query the size of a
screen or display so we shouldn't allow that either.