Re: Q: child frames on ttys

[Eli Zaretskii <eliz@gnu.org>]

> 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.