diff -ur metacity-2.30.0-orig/src/core/screen.c metacity-2.30.0/src/core/screen.c
--- metacity-2.30.0-orig/src/core/screen.c	2010-01-15 00:31:32.000000000 +0000
+++ metacity-2.30.0/src/core/screen.c	2010-05-04 22:07:19.000000000 +0100
@@ -1281,7 +1281,10 @@
       entries[i].title = window->title;
 
       win_pixbuf = get_window_pixbuf (window, &width, &height);
-      if (win_pixbuf == NULL)
+      /* Disable the composited alt-tab switcher as a work-around
+         for http://bugzilla.gnome.org/show_bug.cgi?id=504729  */
+      /*if (win_pixbuf == NULL)*/
+      if (1)
         entries[i].icon = g_object_ref (window->icon);
       else
         {
