title: Jquery Ui Datepicker month/year dropdown is not working in popup in latest firefox
body: <p>Somehow my jQuery UI Datepicker Month/Year Dropdown not working in any popup in latest firefox .</p>
  
  <p>When I click on Month or Year Dropdown, the options list doesn't appears.</p>
  
  <p>Here is my Popup &amp; Datepicker Code:</p>
  
  <pre><code>$( "#dialog-form" ).dialog({
      modal: true
  });
  
  $("#datepicker").datepicker({
      changeMonth: true,
      changeYear: true
  });
  </code></pre>
  
  <p>I prepared a demo on JSfiddle too:</p>
  
  <p><a href="http://jsfiddle.net/469zV/2/">http://jsfiddle.net/469zV/2/</a></p>