bug#9366: Display geometry change hook

[martin rudalics]

>> Has anyone ever confirmed that it correctly handles the full-screen
>> frames?
>
> I don't know.  I don't have a system to try that.

Maybe someone on Windows could give it a try:

(1) With an Emacs frame run 'toggle-frame-fullscreen' (F11).

(2) Change the resolution of the monitor the frame appears on.

(3) Look whether the frame is still fullscreen.

> Do we use XRANDR to query the display geometry?

If they are available, Emacs tries XRANDR first and, if that fails,
XINERAMA next.

> I didn't mean MS-Windows events (a.k.a. "messages"), I meant events in
> the Emacs event queue.  A message coming from the window manager
> doesn't have to be converted to an Emacs event, it can be handled
> directly.

You mean that we'd have to put a function running the hook into the
event queue when no input is allowed?  And running 'gui_set_fullscreen'
OTOH can be handled directly?

martin