<!doctype html>
<html>
  <head>
    <title>subscriptshift/superscriptshift underover</title>
    <meta charset="utf-8"/>
  </head>
  <body>

    <math>
      <munder>
        <mo>&sum;</mo>
        <mspace width="10px" height="10px" mathbackground="red"/>
      </munder>
      <mover>
        <mo>&sum;</mo>
        <mspace width="10px" height="10px" mathbackground="red"/>
      </mover>
      <munderover>
        <mo>&sum;</mo>
        <mspace width="10px" height="10px" mathbackground="red"/>
        <mspace width="10px" height="10px" mathbackground="red"/>
      </munderover>
    </math>

  </body>
</html>