Kévin Le Gouguec <kevin.legouguec@gmail.com> writes:

>>> AFAICT, this is the simplest way to fix org-fontify-whole-heading-line
>>> and org-fontify-whole-block-delimiter-line for Emacs ≥27.  These user
>>> options work under the assumption that simply fontifying the final
>>> newline is enough to extend attributes past EOL.
>>
>> Nevertheless, I would like to see the :extend attribute applied only
>> under the above options; there's the set-face-extend function for
>> doing that.
>
> OK.  That's more or less what I had in mind when I went into my
> "long-term fix" ideas.
>
> Note that Org tries to support older Emacs versions.  AFAICT, with my
> patch, (1) org-fontify-whole-heading-line is fixed for Emacs 27, (2) no
> further modification is needed for Emacs ≤26.
>
> I can try to cook up a patch based on set-face-extend instead, with all
> the fboundp fun that entails to prevent byte-compiler warnings with
> older Emacs versions.  I'm not sure where the calls to set-face-extend
> should be inserted; when setting up the major mode?

Since all the other threads I'm following are stalled, I've taken a stab
at this: