gistfile1.php

<?php

class My_Walker_Nav_Menu extends Walker_Nav_Menu {
  function display_element( $element, &$children_elements, $max_depth, $depth=0, $args, &$output ) {

    if ( !$element )
      return;

    $id_field = $this->db_fields['id'];

    //display this element
    if ( is_array( $args[0] ) )
      $args[0]['has_children'] = ! empty( $children_elements[$element->$id_field] );
    $cb_args = array_merge( array(&$output, $element, $depth), $args);
    call_user_func_array(array(&$this, 'start_el'), $cb_args);

    $id = $element->$id_field;

    // Remove child items if item is not current
    if (!$element->current && !$element->current_item_ancestor && isset( $children_elements[$id])) {
      unset( $children_elements[ $id ] );
    }

    // descend only when the depth is right and there are childrens for this element
    if ( ($max_depth == 0 || $max_depth > $depth+1 ) && isset( $children_elements[$id])) {

      foreach( $children_elements[ $id ] as $child ){

        if ( !isset($newlevel) ) {
          $newlevel = true;
          //start the child delimiter
          $cb_args = array_merge( array(&$output, $depth), $args);
          call_user_func_array(array(&$this, 'start_lvl'), $cb_args);
        }
        $this->display_element( $child, $children_elements, $max_depth, $depth + 1, $args, $output );
      }
      unset( $children_elements[ $id ] );
    }

    if ( isset($newlevel) && $newlevel ){
      //end the child delimiter
      $cb_args = array_merge( array(&$output, $depth), $args);
      call_user_func_array(array(&$this, 'end_lvl'), $cb_args);
    }

    //end this element
    $cb_args = array_merge( array(&$output, $element, $depth), $args);
    call_user_func_array(array(&$this, 'end_el'), $cb_args);
  }
}

?>