private function renderDropDownListOptions($writer, $options, $selected = null)
{
foreach ($options as $k => $v) {
$writer->addAttribute('value', $k);
if ($k == $selected) {
$writer->addAttribute('selected', 'selected');
}
$writer->renderBeginTag('option');
$writer->write($v);
$writer->renderEndTag();
}
}