To properly resize clients, we need to send them configure events
with the size we computed from the constraint system, and
then check if the new size they ask is compatible with
our expectation.
Note that this does not handle interactive resizing yet, it
merely makes the API calls work for wayland clients.
https://bugzilla.gnome.org/show_bug.cgi?id=707401
Add a new interface, gtk_shell, than can be used by gtk to
retrieve a surface extension called gtk_surface, which will be
used to communicate with mutter all the GTK extensions to EWMH
https://bugzilla.gnome.org/show_bug.cgi?id=707128
Add support for GTK application menus
To do so, we need to be able to set surface state before creating
the MetaWindow, so we introduce MetaWaylandSurfaceInitialState as
a staging area.
The gtk-shell-surface implementation would either write to the
initial state, or directly to the window.
At the same, implement set_title and set_class too, because it's
easy enough.
https://bugzilla.gnome.org/show_bug.cgi?id=707128
