new text property

[Colin Walters <walters@gnu.org>]

Hello,

Emacs 21.4 will have a new text property `font-lock-face'.  I would
personally like to see support for this property in XEmacs too, so the
authors of externally distributed modes can use it easily and keep their
code portable, and also to keep Emacs and XEmacs from diverging more.

The rationale for this change is that it easily allows "special" modes
to have their fontification controlled by M-x font-lock-mode, rather
than having to set a variable like `cvs-highlight', `Info-fontify', or
tracking down a -face variable and setting it to `default'.

Emacs actually doesn't implement this variable in the core C code;
instead, we added a new variable `char-property-alias-alist' which
allows properties to have alternative names.  M-x font-lock-mode can
then add and delete `font-lock-face' as an alias for the `face'
property.  There are other neat things one can do with this variable
too.

It would be nice if XEmacs could support `char-property-alias-alist' in
its entirety (I bet all you need to change is `extent-get'), but I'd be
satisfied with just implementing support for `font-lock-face', however
you choose to do it.

What do you (XEmacs people) think?

If you're interested in all the details of how we eventually arrived at
this solution, see the thread entited "kill ring menu" on emacs-devel
(we really should have chosen a different subject title at some
point...).