Re: Question about dubious code for terminal frames

[Eli Zaretskii]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: emacs-devel@gnu.org,  rudalics@gmx.at
> Date: Mon, 02 Sep 2024 16:11:34 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > What exactly is the problem?  Doesn't change_frame_size support child
> > frames?
> 
> Not on terminals, no, for exactly the reason that adjust_frame_size for
> terminal frames sets the terminal's size. So, when I opened a new child
> frame of size 20x30 suddenty the terminal had size 20x30. And the
> innocent root frame redisplay got an emacs_abort because it wrote
> outside of that range because the root frame was of course much larger.

OK, but the behavior on TTY terminals in this regard should be exactly
the same as on GUI terminals, when you drag the frame's border with
the mouse.  So I very much hope there's code in Emacs that you can
simply copy or maybe even just call.

> I personally think it's wrong to set FrameCols/Rows in this way in
> adjust_frame_size. From my POV, it's should be a physical property of
> the terminal that Emacs does not change. If we can't determine the size
> of the terminal (and I wonder how often that is the case), we should
> devise a way to let the user specify the size, but without the current
> magic. 

But with the current proliferation of terminal emulators whose window
can be resized, what other choice do we have when the only source of
information about the resize is SIGWINCH?  How else can we update the
Emacs notion of the frame's size?