bug#19990: 24.4; Bad resizing interaction when WM ignores size hints

[Yuri D'Elia <yuri.delia@eurac.edu>]

On 03/06/2015 10:21 AM, martin rudalics wrote:
> The OP said that:
> 
>     I force the emacs frame to take the height of the entire screen.
> 
> So this looks like a fullheight frame to me without, apparently,
> explicitly specifying it as such.

I should have never said 'full screen height', since this keeps
confusing you. In my particular configuration, I have no window borders,
so two windows side-by-side will automatically fit the screen height.
This is *not* a special case for a tiling window manger.

A tiling window manager will force the frame to fit a screen region,
_possibly_ ignoring size hints. That's all there is to it. It does that
*intentionally*, since you can imagine that having gaps between the
tiles is just plainly annoying. In a side-by-side configuration, you
don't want gaps on the lower corner of the screen.

> Maybe the OP's problem is that the Window manager conceptually gives
> Emacs the full height of the screen and Gtk+ is not aware of that.
> Maybe also Gtk+ doesn't even understand fullheight.  At least I can't
> detect an entry for it in GtkWindowPrivate which OTOH has a 'tiled'
> entry.

The problem with Gtk+ is that it tries to handle hints both on behalf of
the window manger and on the client. I have *no* clue of why it does
that. Maybe to handle TWM? Or more probably to handle the "Windows" port
which has no such feature?

The second issue with Gtk+ is that it notifies the application while
doing his own hint handling (or again, is that intentional?).

I would be perfectly happy to discuss this issue with Gtk+ folks, but I
remember that back in Gtk 1.3/2.0 days, many of my patches where
rejected since they fixed behavior that wasn't really intended "for the
common user", whatever that means. Gtk 3 seems to have regressed even
more in this area, so I just gave up in trying to argue.

To sum up, however, what about this:

Since we receive the first ConfigureNotify event with the unhinted
width/height, we *can* detect that the size hints have been ignored.
Couldn't we disable them at that point? This would fix Gtk+ trying to do
a reconfiguration attempt and remove the following two useless events.
This looks like a simple fix that would already improve the current
configuration, but I would need experience with the Mac/Win port to tell
if Gtk would fail in this scenario. Maybe an "ifdef X11" is required.

The question then becomes: would actually be possible to set the hints
immediately back on, so that in a further resize request the WM sees the
hints, but *without* having Gtk+ do it's mess? This would mean that we
would need to set the hints back on when the resize request has been
fully settled. Tricky. Setting them back-on on a further repaint/focus
in/out event is either too late or not enough.

As mentioned in my first request, this is a minor nuance fix for folks
with tiling window managers. My point is "can we handle it better?".