jquery-ui bug
https://bugs.jqueryui.com/ticket/9125#comment:14
HTML
<link rel="stylesheet" href="http://code.jquery.com/ui/1.10.1/themes/base/jquery-ui.css">
<script src="http://code.jquery.com/ui/1.10.1/jquery-ui.js"></script>
<div id="dialog">
<input id="datepicker">
</div>
JavaScript
$("#datepicker").datepicker();