Re: buffer-face-set changes the fringe, is it a bug?

[Eli Zaretskii]

> Date: Sun, 5 Jul 2020 18:25:33 +0200 (CEST)
> From: Gregory Heytings via "Emacs development discussions." 
> <emacs-devel@gnu.org>
> 
> > Thanks, I clarified the meaning of FACE in that case.
> >
> 
> Okay, the meaning is clear now.  But, IMO, it would be better to change 
> this behavior as follows:
> 
> "The optional @var{face} names a face whose foreground and background 
> colors are to be used to display the bitmap; this face is automatically 
> merged with the @code{fringe} face.  If @var{face} is omitted, that means 
> to use the *@code{fringe}* face."
> 
> I at least would expect that the default behavior when displaying 
> something in the fringe would be to use the fringe face.

IMO, you are looking at this feature from the wrong angle.  This is a
"replacing" 'display' property that covers some buffer text or overlay
string, and is displayed instead of that buffer text or overlay
string.  Therefore, the natural source of the face information is the
face of the text which is covered by the 'display' property, not the
face of the place where the bitmap is drawn.

In any case, this behavior is very old, so changing it is quite out of
the question.  Especially since having the behavior you consider to be
a better one is so easy.