bug#59141: 28.1.90; Face :extend when all the line but trailing \n is invisible

[Kévin Le Gouguec]

Eli Zaretskii <eliz@gnu.org> writes:

> I said many times that people shouldn't willy-nilly use the :extent
> attribute, just because it looks cooler in some situation.  The intent
> was and still is for faces not to have this attribute set, with very
> few very special exceptions, like the 'region' face.  But people don't
> listen...

FWIW, my motivation for setting :extend on outline headings doesn't stem
from aesthetics.

Clearly delineating "sections" with colored backgrounds that span the
whole window width is a neat visual aid, IME; that's just one more guide
for the eye to exploit when e.g. locating the next same-level heading
(for those who like to look before they leap), getting a sense of how
"long" a section is (in terms of lines if expanded, or subsections if
folded), etc.

(Other people's sensibilities will necessarily differ, e.g. they might
find a document's structure easier to scan visually without distracting
colored backgrounds.  I certainly don't mean to imply that :extending
heading backgrounds would be "objectively" better, only that it would be
genuinely helpful for _some_ folks)

So this "visual aid" aspect is why I suspect reporters think being able
to :extend outline heading backgrounds is about as desirable as
:extending the hl-line or region faces, and it's a shame it breaks down
when folding.

It's not a critical feature to be missing, and that motivation does not
invalidate the implementation challenges you highlight.  I just wanted
to spell this point out FTR, as I didn't feel "it looks cooler" conveyed
it quite as convincingly 🙂