Re: Implementing child frames on terminal

[Eli Zaretskii]

> From: Akib Azmain Turja <akib@disroot.org>
> Cc: luangruo@yahoo.com, monnier@iro.umontreal.ca, emacs-devel@gnu.org,
>  ibluefocus@outlook.com
> Date: Thu, 14 Jul 2022 13:14:18 +0600
> 
> You misunderstood my question.  I meant: is there any real reason to
> share the glyph memory of the parent and the child frame?

Yes: the last stage of TTY redisplay uses only the frame glyph matrix,
it doesn't use glyph matrices of the windows.  For child frames, this
translates into using only the frame matrix of the topmost frame.  (As
I proposed at the beginning of this discussion, I would not even
maintain frame matrices for child frames, only window matrices.)

> We can just copy the visible part of child frame matrix to parent
> frame matrix, which IMHO won't cause any noticeable slowdown
> compared to X.

As I explained earlier, I don't understand why would we want to incur
this slowdown, however unnoticeable.  Unlike on GUI displays, TTYs
have a fixed number and positions of character cells, and not to use
this fact sounds silly to me, especially since the existing code
already does that.