Drupal 6: Menu Item mit Query Parameter

/**
 * Implementation of theme_menu_item_link()
 */
function THEMENAME_menu_item_link($link) {
  if (empty($link['localized_options'])) {
    $link['localized_options'] = array();
  }
 
  // Add the query param to the url
  if ($link['href'] == 'user/login' && $_GET['popup']) {
    $link['localized_options']['query'] = 'login=popup';
  }
 
  return l($link['title'], $link['href'], $link['localized_options']);
}