bug#41810: 28.0.50; [ELPA] adaptive-wrap: Fontify wrap-prefix

[Stefan Monnier <monnier@iro.umontreal.ca>]

> The comment's continuation line starts with ";;;;".  I see two problems
> with this:
>
> 1. The padding characters are not propertized, so we get two fontified
>    semicolons, then two unfontified semicolons.

That looks ugly, indeed.  IIRC the reason is that when we extract the
prefix from the buffer, font-lock hasn't applied its `face` text
property yet.

> 2. Visually, this looks sort of cluttered.  I have searched Debbugs and
>    emacs-devel for a rationale for using (substring fcp -1) instead of
>    unconditionally using spaces, but I could not find any.

I think it just seemed like a good idea.  I suspect it's a matter of taste.
Not sure if it's important enough to justify offering both behaviors.

> See second screenshot, taken from emacs -Q -rv, with:

That's ugly, indeed.  Not sure whether the problem really comes from nor
where it should be fixed, but it's clearly a bug.


        Stefan