My own HTML_Template_Flexy_Element

The manual states: string $element->toHtml () returns the HTML to represent the object. If you wish to implement your own element, you only need to implement this method, and assign it to the element array.. I have: $this->elements['ticket_type'] = new PullDownMenu('type', $options); But in the compiled template, print_r() outputs: HTML_Template_Flexy_Element Object (

    [tag] => select
    [attributes] => Array
        (
            [name] => type
        )

    [children] => Array
        (
        )

    [override] =>
    [prefix] =>
    [suffix] =>
    [value] =>

) How should custom elements be implemented?