(Face Functions): Mention define-obsolete-face-alias.

doc/lispref/ChangeLog

+2009-09-01  Glenn Morris  <rgm@gnu.org>
+
+	* display.texi (Face Functions): Mention define-obsolete-face-alias.
+
 2009-08-26  Ulrich Mueller  <ulm@gentoo.org>
 
 	* nonascii.texi (Character Codes): Fix typos.

doc/lispref/display.texi

@@ -2629,6 +2629,12 @@ makes @code{modeline} an alias for the @code{mode-line} face.
 (put 'modeline 'face-alias 'mode-line)
 @end example
 
+@defun define-obsolete-face-alias obsolete-face current-face &optional when
+This function defines a face alias and marks it as obsolete, indicating
+that it may be removed in future.  The optional string @var{when}
+indicates when the face was made obsolete (for example, a release number).
+@end defun
+
 @node Auto Faces
 @subsection Automatic Face Assignment
 @cindex automatic face assignment