Juri Linkov <juri@linkov.net> writes:

>>> Could you send a screenshot that shows a newline with the :extend
>>> attribute as the final character of the outline in magit?
>>
>> See attached, showing a recent revision from emacs.git master, with the
>> diff completely folded (1.png) with hunks folded (2.png) and completely
>> unfolded (3.png).
>>
>> I hope I understood your suspicion correctly and my answer was relevant?
>> Let me know if I misunderstood.  FWIW "insert a supplementary newline
>> before headings" is indeed a well-known workaround in the Org community.
>
> Thanks for the screenshots.  What I still don't see is an example
> where a newline at the end of the last line of the outline (diff hunk)
> has some non-default face.  I.e. the same as in your test case in
> https://debbugs.gnu.org/52587#13

All of them do, unless I misunderstand something?  I.e. all hunks are
painted in #100f10, the background of magit-diff-context-highlight,
while the default face has background #000000.

Attaching an… "annotated" version of the previous screenshots.  To
recap:

* default background is #000000,

* magit-diff-file-heading-highlight background is #203448,

* magit-diff-hunk-heading-highlight background is #323232,

* magit-diff-context-highlight background is #100f10,

* when a hunk is folded, the background for the final newline of the
  hunk content (#100f10) does not "bleed" into the hunk header's
  extension,

* instead, this hunk header's extension keeps the color it has when the
  hunk is unfolded, i.e. the same color as the rest of the header
  (#323232).

Let me know if that clarifies things, or if I've misunderstood what you
are asking for.