Index: includes/menu.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/menu.inc,v
retrieving revision 1.411
diff -u -p -r1.411 menu.inc
--- includes/menu.inc	24 Sep 2010 00:37:41 -0000	1.411
+++ includes/menu.inc	24 Sep 2010 16:03:58 -0000
@@ -3469,7 +3469,19 @@ function _menu_router_build($callbacks) 
       $item['access callback'] = intval($item['access callback']);
     }
 
+    // We first set all defaults that will evaluate to TRUE, then do an
+    // array_filter() to ensure we don't have NULL values set.
+    // Afterwards, we set all defaults that are equal to FALSE.
     $item += array(
+      'title callback' => 't',
+      'tab_root' => $path,
+      'path' => $path,
+    );
+    $item = array_filter($item);
+    $item += array(
+      'title' => '',
+      'weight' => 0,
+      'module' => '',
       'access arguments' => array(),
       'access callback' => '',
       'page arguments' => array(),
@@ -3477,15 +3489,12 @@ function _menu_router_build($callbacks) 
       'delivery callback' => '',
       'block callback' => '',
       'title arguments' => array(),
-      'title callback' => 't',
       'theme arguments' => array(),
       'theme callback' => '',
       'description' => '',
       'position' => '',
       'context' => 0,
       'tab_parent' => '',
-      'tab_root' => $path,
-      'path' => $path,
       'file' => '',
       'file path' => '',
       'include file' => '',