$msg =& $this->overview[$id];
$parents =& $this->getReferences($message);
while (!empty($parents) && ($msg->parent === $msg || is_null($msg->parent))) {
$msg =& $this->overview[$id];
$parents =& $this->getReferences($message);
while (!empty($parents) && ($msg->parent === $msg || is_null($msg->parent))) {