<!DOCTYPE html>
<html class="reftest-wait">
   <head>
     <title>mo@movablelimits</title>
     <meta charset="utf-8"/>
     <script type="text/javascript">
       function doTest() {
         document.getElementById('a').removeAttribute('movablelimits');
         document.documentElement.removeAttribute("class");
       }
       window.addEventListener("load",doTest, false);
     </script>
    </head>
    <body>
    <math>
      <munder>
          <mo id="a" movablelimits="false">∑</mo>
          <mi>x</mi>
      </munder>
    </math>
    </body>
</html>