bug#14157: 24.3.50; Improve facemenu.el: Better "integration" with other libraries

[Eli Zaretskii <eliz@gnu.org>]

> From: Jambunathan K <kjambunathan@gmail.com>
> Date: Wed, 10 Apr 2013 09:20:45 +0530
> 
> 
> Should facemenu.el use overlays for highlighting?

Why should it?  Text properties can do everything that facemenu needs
to do, and they scale much better.

> One main disadvantage of not using overlays is that Orgmode cannot be
> used in conjunction with enriched mode.

Org mode already strains the limits of the Emacs display engine, with
its massive use of invisible text and various display properties.
Adding yet more overlays to it, for such a mundane task as
highlighting text, would be extremely unwise.

If facemenu cannot work with Org, either facemenu should be changed to
be able to do that, or some new feature should be added to Org to
allow the highlighting functionality.

> The notion of persistence of face properties (as in serializing/encoding
> face properties in to the edited text - either tex mode, sgml mode or
> more importantly enriched mode) is "in built" in to facemenu.el.  It is
> not necessary that a highlighted text be encoded/persisted in to the
> saved file.  I could be reviewing a piece of text and might want to do
> "on the go" highlighting some phrases to take notes without saving it
> anyway.

I don't understand what are you talking about.  facemenu doesn't save
the faces, it just allows to define and put them.  Maybe you are
thinking about Enriched text mode.

The usual way Emacs uses faces is that faces are re-applied anew each
time a file is visited.  Enriched does what it does because plain text
files don't have enough structure to re-apply the faces.