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

[Gregory Heytings]

> > Why not make that an error instead?
>
> Because it is not an error, it's an entirely valid usage.

That you do not want to change the code is xdisp.c is one thing, with 
which I'm ok.

That you claim that it's a "entirely valid usage" or a "minor issue" is 
another, and it is plain wrong.  I cannot imagine a single scenario where 
what someone positively wants is to have the colors of an element in the 
fringe change when, for example, the text is scaled up and down.  If you 
have such a case in mind, please provide it.  I filed a bug report against 
diff-mode.el, in which this happens.

What is true is that the default colors of the fringe (black on light 
gray) and the default colors of the buffer (black on white) are close 
enough that many users do not see the difference when this happens.  I 
happen to use a different color for the fringe, and I'd bet I'm not the 
only one to do this.

Note the explanation in NEWS.22, when this display property was 
introduced: "Format is `display (left-fringe BITMAP [FACE])', where BITMAP 
is a symbol identifying a fringe bitmap, either built-in or defined with 
`define-fringe-bitmap', and FACE is an optional face name to be used for 
displaying the bitmap ***instead of the default `fringe' face***. When 
specified, FACE is automatically merged with the `fringe' face."

I took the liberty to add one more message to this already too long 
thread, to answer RMS's question.  Now I stop arguing again.

Thank you for your attention.

Gregory