Re: Making TTY menus more visual

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 13 Oct 2020 18:59:01 -0700
> From: Jared Finder <jared@finder.org>
> Cc: emacs-devel@gnu.org
> 
> > Are you sure posn-window cannot return a frame?  For example, on a
> > TTY, I get this:
> > 
> >   (posn-at-x-y 0 0 (selected-frame))
> >    => (#<frame F1 069b0190> nil (0 . 0) 0)
> > 
> > And (0,0) are coordinates in the frame's menu bar.
> 
> A ha! A bug! Behavior is different depending on options selected at 
> configure time.
> 
> Behavior with ./configure --with-x=no:
> (posn-at-x-y 0 0 (selected-frame))
> => (nil nil (0 . 0) 0)
> (selected-frame)
> => #<frame F1 0x55be32685d38>
> 
> Behavior with ./configure --with-x=yes:
> (posn-at-x-y 0 0 (selected-frame))
> => (#<frame F1 0x561fedbc6b98> nil (0 . 0) 0)
> (selected-frame)
> => #<frame F1 0x561fedbc6b98>
> 
> This bug has been around a while, on Debian (Emacs 26.1), emacs-no-x vs 
> emacs-gtk shows the same difference in behavior.

Right.

> Do you have a preference for a fix? Some options:
> [...]
> I found at one other behavior difference, if you pass in out of bounds 
> coordinates (example: 1000 0 for a TTY), --with-x=no you get the value 
> as if you passed in 0 0, but --with-x=yes assumes the coordinate is 
> valid. There are probably other differences. I can do a pass over this 
> function, I'd like to know the razor to use.

These all are due to the same problem: too early exclusion of code in
builds --without-x.  I think I fixed this on the emacs-27 branch.
(While at that, I also fixed the documentation by adding the
description of the POSITION in this case.)

I don't think it's right to change the meaning of the WINDOW part of a
click even at this point: the current behavior is very old, and the
fact it's called WINDOW doesn't mean it cannot be a frame in some
cases, assuming we document that.

> > Does it make sense to install this patch on its own?  If so, we can
> > install it without waiting for the legal paperwork, the changes are
> > small enough.
> 
> Yes, the issue existed prior to my changes when using TMM in a terminal.

OK, I will install that soon.  Thanks.