bug#36858: 27.0.50; display bugs with display-fill-column-indicator-mode

[Drew Adams <drew.adams@oracle.com>]

Not really intending to jump in here, but I
wonder if an enhancement like one of these
would be possible/useful.  No idea whether
this really makes sense or is relevant to
this thread - just thinking out loud.

* Add a :set keyword for `defface'.
* Add an optional SET-FUNCTION arg to
  `face-spec-set'.  It would be invoked just
  after the face gets set to SPEC.

Presumably, with something like that, code
could specify, for a given face, that setting
its attributes in certain ways would entail
performing some additional action.

For example, if background is set, without
also underlining (example - not limited to
this case), then the face would not be
applied to an eol char.

---

Otherwise, isn't it possible for the Org
code to check the face attributes and act
accordingly wrt the eol char?

Yes, this is a more general issue than just
for Org.  That's why I was thinking of
something like the suggestion above: have
face-setting let you know what the current
case is (e.g. have it set a variable, which
you can test).