The demo is in an iframe, in which they use jQuery UI 1.9.2 and jQuery 1.8.3.
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1/jquery-ui.min.js"></script>
JΛ̊KE
I believe that recent changes to the position utility are preventing it from currently working and I would love some help figuring out how to fix this issue. The working demo of the widget's position option is located here, but that uses jQuery 1.4.4, and more recent versions of jQuery prevent the multiselect elements from opening.