/**
* Renders the HTML response text
*
* @return string
*/
private function _getDisplay()
{
// The header may contain nothing at all,
// if its content was already rendered
// and, in this case, the header will be
// in the content part of the request
$retval = $this->_header->getDisplay();
$retval .= $this->_HTML;
$retval .= $this->_footer->getDisplay();
return $retval;
}