public function prepend($text, $url=null, $type=null, $shorttext=null, $key=null, pix_icon $icon=null) {
        $children = $this->children;
        $childrenclass = get_class($children);
        $this->children = new $childrenclass;
        $node = $this->add($text, $url, $type, $shorttext, $key, $icon);
        foreach ($children as $child) {
            $this->children->add($child);
        }
        return $node;
    }