Specify a PHP callback here that can be used to render your widget.<br />
<br />
Callback arguments:
<ol>
	<li><code>\XF\Widget\AbstractWidget $widget</code><br />This widget. From this you can access the <code>WidgetConfig</code> object and the <code>\XF\App</code> object in order to fetch data and render a template by returning the <code>$widget->renderer()</code> object.</li>
</ol>