bug#56691: outline-minor-mode displays navigation arrow buttons as emojis

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: larsi@gnus.org,  rpluim@gmail.com,  56691@debbugs.gnu.org,
>   hello@paulwrankin.com
> Date: Mon, 01 Aug 2022 20:16:20 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > That's orthogonal, and can only be done once the predicate is
> > implemented.
> 
> How so?  FC_COLOR is used during the font matching process, so it can
> only be a font spec or entity attribute.
> 
> So a display-specific predicate could only be implemented like this:
> 
>   (defun display-color-font-p (frame)
>     "DOC"
>     (find-font (font-spec :color t) frame))

I thought we wanted a capability indication, not something that
actually looks for installed fonts.  AFAIU, if there are no color
fonts on the user's system, the above will tell Emacs color fonts
aren't supported.  That's not what we wanted, based on earlier
discussions.