public function getParentId($id)
    {
        $path = $this->getProperty($id, self::PATH);
        array_pop($path);

        return empty($path)
            ? null // the given item is the root
            : array_pop($path);
    }
public function getParentId($id)
    {
        $path = $this->getProperty($id, self::PATH);
        array_pop($path);

        return empty($path)
            ? null // the given item is the root
            : array_pop($path);
    }
public function getParentId ( $ id ) { $ path = $ this -> getProperty ( $ id , self :: PATH ) ; array_pop ( $ path ) ; return empty ( $ path ) ? null // the given item is the root : array_pop ( $ path ) ; }
Returns the id of the parent layout item

@param string $id The id or alias of the layout item

@return string|null The id of the parent layout item or null if the given item is the root
Returns the id of the parent layout item