Re: Q: child frames on ttys

["Gerd Möllmann" <gerd.moellmann@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Gerd Möllmann <gerd.moellmann@gmail.com>
>> Cc: rudalics@gmx.at,  emacs-devel@gnu.org
>> Date: Sat, 31 Aug 2024 16:00:22 +0200
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> The simplest such function is of course the identity function, which
>> >> means child and root share the same face cache. With the consequence
>> >> that changing named faces on the child modifies faces of the root. Not
>> >> nice, but simple.
>> >> 
>> >> As I said, I'm not sure about this. I could also think of redefining the
>> >> concept of face id to something containing the frame or cache holding
>> >> the face's definition. Which could be done in more than one way. And so
>> >> on, but it's certainly some work.
>> >> 
>> >> What do people think?
>> >
>> > FWIW, I don't see why this would be a serious limitation.  After all,
>> > by default we define the faces identically on all frames, and Lisp
>> > programs that want to have different faces on different frames need to
>> > actively opt in.  Most don't.
>> 
>> Thanks.
>> 
>> I think I'm mostly concerned of the seemingly harmless background-color
>> frame parm, and what else there is which change the default face on a
>> frame. I could imagine that one would want to do that for child frames.
>> Like a frame for completion candidates, for example.
>
> We should document that this doesn't work on TTY displays, and let
> applications deal with that.
>
>> Hm. I think I'll leave that as is for now, i.e. simply share the
>> face cache with the root. It could be changed later, and it's pretty
>> independent of the rest, I'd say. At least as far as I can see now.
>
> Right.  Just please don't forget documenting it.

Just wanted to mention that I had an idea yesterday how to solve that
problem without making broad changes outside of the tty code. The idea
is to write a function that maps an (x, y) position in a
matrix the frame holding the realized face at that position.

One ugly difference less between ttys and GUI.