bug#16514: 24.3.50; Region overlay looks bad on refined hunks in diff-mode

[Dmitry Gutov]

On 06.12.2020 17:58, Eli Zaretskii wrote:
> > From: Kévin Le Gouguec<kevin.legouguec@gmail.com>
> > Date: Sun, 06 Dec 2020 16:39:04 +0100
> > Cc:16514@debbugs.gnu.org, Dmitry Gutov<dgutov@yandex.ru>
> >
> > As long as point does not go past the refinement (before the comma), the
> > region's background has the region face's background.
> >
> > Once point moves past the refinement, only non-refined parts keep the
> > region face's background; refined parts keep the refinement background.
> This is expected, since we sort overlays so that the one whose extent
> is larger wins.
>
> To do anything else the overlays should have priorities.

So it's probably correct from the low-level primitives POV.

But is this a good UI? And shouldn't we maybe tweak the high-level 
implementation (perhaps, the way how the refinements are applied) so 
that the behavior is better?