bug#42184: 27.0.91; org-fontify-whole-heading-line does not work in emacs 27

[Kyle Meyer]

Kévin Le Gouguec writes:

> Here is a variant of the previous patch, which correctly resets :extend
> to nil if the user disables the relevant options (after reverting the
> current buffer, or for newly opened ones).
>
> This ends up looking similar to what Org does for org-hide; IMO this
> seems like the most straightforward short-term fix.  In the long run,
> these user options would probably deserve :set functions.

Thanks for working on this fix.  I of course can't speak for Bastien or
Nicolas, but this patch looks fine to me.  Assuming it's okay with Eli,
I'd suggest applying it to the emacs-27 branch.  (Once applied, I'd port
it to the Org repo, as I do with other changes in the Emacs repo that
touch Org files.)

Upstream in the thread you wrote:

> Relatedly (but not crucial to solving this bug), should org-block and
> org-block-background also have :extend t?  It would make sense to me
> since they delimit visual "blocks".

That would make sense to me as well.  (org-block-background hasn't
existed since v8.3, though.)