private static function getBindingValue ($prop, Component $component, &$error)
  {
    $error = $l = false;
    try {
      $l = ob_get_level ();
      $v = $component->getComputedPropValue ($prop);
    }
    catch (\Exception $e) {
      $error = true;
      while (ob_get_level () > $l)
        ob_end_clean ();
      return "<b style='color:red'>ERROR</b>";
    }
    return $v;
  }