bug#57693: 29.0.50; Is there a more reliable version of `char-displayable-p'?

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: stefankangas@gmail.com, yantar92@gmail.com, 57693@debbugs.gnu.org
> Date: Sun, 19 Feb 2023 14:19:58 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > We could have a special glyphless-char-display table for mode-line and
> > header-line.  Buffer-local values don't apply well to those anyway,
> > because they display strings, not buffer text.
> 
> Then, also margins, tab-bar, and menu-bar?

Margins show buffer text.  Tab bar does not belong to any buffer.
Menu bar is not relevant (and is displayed by toolkits in most builds
anyway).

> I feel that simply allowing text properties will be less cumbersome
> from the point of view of API.

Not from the POV of the implementation, though.