bug#14471: 24.1.50; GTK3 shows resize handle which cannot be disabled

[martin rudalics]

>> Start "emacs -Q" that was compiled with --with-x-toolkit=gtk3 from bzr.
>> You should see a resizing triangle button in the lower right-hand
>> corner, as in http://www.nexoid.at/tmp/emacs-triangle.jpg
>>
>> This resizing button is useless on all tiling window managers. If you
>> remove the check for GTK 3 from gtkutil.c (~ line 1159), things work
>> fine again (and I believe this check is erroneous anyway, why only
>> disable it on GTK != 3?). After recompiling, the resulting emacs -Q
>> looks like this: http://www.nexoid.at/tmp/emacs-no-triangle.jpg
>
> I'm not seeing this resize grip on either of these:
>
> GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.4) of
> 2019-02-03, modified by Debian
>
> GNU Emacs 27.0.50 (build 14, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
> of 2019-09-21
>
> Are you still seeing this on a recent version of Emacs, for example the
> latest version 26.3?  If I don't hear back from you in a couple of
> weeks, I'll assume this is no longer an issue and close the bug.

Ultimately, the decision whether to show a grip or not must be left to
the window manager.  A tiling window manager should suppress it for
all windows it shows.  The check mentioned by the OP is only needed
for handling an apparent bug in a GTK 2 library

  /* gtk_window_set_has_resize_grip is a Gtk+ 3.0 function but Ubuntu
     has backported it to Gtk+ 2.0 and they add the resize grip for
     Gtk+ 2.0 applications also.  But it has a bug that makes Emacs loop
     forever, so disable the grip.  */
#if (! defined HAVE_GTK3 \
     && defined HAVE_GTK_WINDOW_SET_HAS_RESIZE_GRIP)
  gtk_window_set_has_resize_grip (GTK_WINDOW (wtop), FALSE);
#endif

and should not be generalized because we would penalize users who do
want to see the grip on non-tiling WMs.  But if worse comes to worst
we could provide an option to always suppress the grip.

martin