Callback that test menu_test_menu_tree_set_path().
function menu_test_menu_trail_callback() {
$menu_path = variable_get('menu_test_menu_tree_set_path', array());
if (!empty($menu_path)) {
menu_tree_set_path($menu_path['menu_name'], $menu_path['path']);
}
return 'This is menu_test_menu_trail_callback().';
}