diff -Naur emacs.old/src/xterm.c emacs.new/src/xterm.c
--- emacs.old/src/xterm.c	Sat Mar  2 00:38:47 2002
+++ emacs.new/src/xterm.c	Sun Mar 10 23:05:22 2002
@@ -1,5 +1,5 @@
 /* X Communication module for terminals which understand the X protocol.
-   Copyright (C) 1989, 93, 94, 95, 96, 1997, 1998, 1999, 2000, 2001
+   Copyright (C) 1989, 93, 94, 95, 96, 1997, 1998, 1999, 2000, 2001, 2002
    Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
@@ -10629,6 +10629,14 @@
 				|| ((unsigned)(orig_keysym) == XK_Num_Lock)
 #endif
 #endif /* not HAVE_X11R5 */
+				/* The symbols from XK_ISO_Lock to
+				   XK_ISO_Last_Group_Lock doesn't have real
+				   modifiers but should be treated similarly
+				   to Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+				|| ((unsigned)(orig_keysym) >=  XK_ISO_Lock
+				    && (unsigned)(orig_keysym) <= XK_ISO_Last_Group_Lock)
+#endif
 				))
 			{
 			  if (temp_index == sizeof temp_buffer / sizeof (short))