Index: wp-admin/includes/plugin.php
===================================================================
--- wp-admin/includes/plugin.php	(revision 11521)
+++ wp-admin/includes/plugin.php	(working copy)
@@ -705,7 +705,7 @@
 }
 
 function add_theme_page( $page_title, $menu_title, $access_level, $file, $function = '' ) {
-	return add_submenu_page( 'themes.php', $page_title, $menu_title, $access_level, $file, $function );
+	return add_submenu_page( 'themes.php', $page_title, $menu_title, $access_level, theme_basename( $file ), $function );
 }
 
 function add_users_page( $page_title, $menu_title, $access_level, $file, $function = '' ) {