I'm building a function that takes a drupal rendered menu and removes the classes from it so that I can pass it to a jQuery function that'll build a menu from it.

The code i'm using for that is:-

<?php
     $tree = menu_tree_all_data("devel-frus");
     $menu = drupal_render(menu_tree_output($tree));
     $nocss = preg_replace('/class=".*?"/', '', $menu);
     echo($nocss);
?>

However menu_tree_output() seems to be only returning the first level of a six level menu when it should be returning the complete menu.

I've tried dsm()'ing $tree to see if all of the menu items are being returned by menu_tree_all_data() and that's fine, however when I dsm() the output of the menu_tree_output() function only the root and first level are returned in the array.

Am I doing something really obviously wrong here?