Index: src/xfaces.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/xfaces.c,v
retrieving revision 1.266
diff -u -r1.266 xfaces.c
--- src/xfaces.c	17 Nov 2002 23:51:19 -0000	1.266
+++ src/xfaces.c	17 Dec 2002 04:31:36 -0000
@@ -422,6 +422,13 @@
 
 Lisp_Object Vtty_defined_color_alist;
 
+/* If non-nil, a function called to perturb faces before final realization.
+   It is passed a lisp-vector containing all the attributes of the
+   fully-specified face, and can change any that it wishes. */
+
+Lisp_Object Vrealize_face_filter;
+
+
 /* Counter for calls to clear_face_cache.  If this counter reaches
    CLEAR_FONT_TABLE_COUNT, and a frame has more than
    CLEAR_FONT_TABLE_NFONTS load, unused fonts are freed.  */
@@ -6691,6 +6698,21 @@ realize_face (cache, attrs, c, base_face
       free_realized_face (cache->f, former_face);
     }
 
+  if (! NILP (Vrealize_face_filter))
+    {
+      /* Call a user-defined function to perturb the face attributes
+	 before realization.  */
+      Lisp_Object lface = Fmake_vector (make_number (LFACE_VECTOR_SIZE),
+					Qunspecified);
+      bcopy (attrs, XVECTOR (lface)->contents,
+	     LFACE_VECTOR_SIZE * (sizeof *attrs));
+
+      safe_call1 (Vrealize_face_filter, lface);
+
+      bcopy (XVECTOR (lface)->contents, attrs,
+	     LFACE_VECTOR_SIZE * (sizeof *attrs));
+    }      
+
   if (FRAME_WINDOW_P (cache->f))
     face = realize_x_face (cache, attrs, c, base_face);
   else if (FRAME_TERMCAP_P (cache->f) || FRAME_MSDOS_P (cache->f))
@@ -7670,6 +7692,13 @@
 Each element is a regular expression that matches names of fonts to
 ignore.  */);
   Vface_ignored_fonts = Qnil;
+
+  DEFVAR_LISP ("realize-face-filter", &Vrealize_face_filter,
+	       doc: /* If non-nil, a function called to perturb faces before final realization.
+It is passed a lisp-vector containing all the attributes of the
+fully-specified face, and can change any that it wishes. */);
+  Vrealize_face_filter = Qnil;
+
 
 #ifdef HAVE_WINDOW_SYSTEM
   defsubr (&Sbitmap_spec_p);