bug#60585: 30.0.50; global-text-scale-adjust shrinks window (was not before)

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Jean Louis <bugs@gnu.support> writes:

> * Gregory Heytings <gregory@heytings.org> [2023-01-07 01:05]:
>> I looked at this problem again, and found that, here at least, it
>> disappears when you turn scroll-bars off.  Is that also the case on
>> your system?
>
> Yes, when I turn off scroll bars, I can't see that problem.
>
> Hints are here:
> https://github.com/ice-wm/icewm/issues/115
>
> so there is something to be set up in Emacs.

I'm sure your window manager is just enforcing a strict increment policy
on to clients.  It is ok for window managers to do this.  And the scroll
bars just happen to be the right size to break the increments with your
specific font, on your specific system.

Normally, window managers only perform increment processing when
configuring a window.  But some listen to the window property and apply
the increment the moment Emacs sets the hints on a frame.  There is
nothing wrong with this behavior, not in the window manager, and not in
Emacs.

On the GTK builds, emacsgtkfixed.c overrides several Xlib functions to
essentially fit the increment to the frame, because otherwise GTK will
set some outrageous increment that will cause Emacs to constantly shrink
on some window managers (not just when the frame font is changed.)

This is not needed in the Xt and no toolkit builds.

If you turn on frame-resize-pixelwise and create a new frame, does the
problem go away?