faces and face variables

["Roland Winkler" <Roland.Winkler@physik.uni-erlangen.de>]

This is an issue that emerged from a discussion with Dan on
proced.el:

The code of proced.el has largely been inspired by the old code of
dired.el. But sometimes this strategy has some pitfalls:

dired.el defines both the faces it uses (like dired-header) and it has
face variables like dired-header-face. Is this strategy still
appropriate for new code? Or is it better to use the faces only?

Font-lock also has such variables, and the code contains the comment
that these variables

  "give users another mechanism for changing face appearance."

If face variables are not considered appropriate anymore and their
use is not recommended anymore, it might help to have a more
definite comment on this issue in font-lock.el (i.e., remove the
above remark and say *only* that these variables are kept for
backward compatibility). Otherwise, users might expect to find this
"feature" for other faces, too.

Thanks,

Roland

PS: I searched emacs-devel for old discussions of this topic, but I
wasn't successful.