/**
* Returns the html id for the container. The id is built by the keys
* of this element and all parents.
*
* @return string
*/
public function getHtmlId()
{
$id = '';
if (is_object($this->parent)) {
$id = $this->parent->getHtmlId();
}
if ($this->key !== '') {
$id .= '-' . $this->key;
}
return $id;
}
