<!DOCTYPE html>
<html>
  <head>
    <title>Stretchy mfenced</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
  </head>
  <body>
    <!-- See bug 687807 -->
    <math >
      <mrow>
        <mo stretchy="false">&#x2192;</mo>
          <munderover>
            <mo stretchy="true">&#x2192;</mo>
            <mtext>AAAAAA</mtext>
            <mtext>BBBBBB</mtext>
          </munderover>
        <mo stretchy="false">&#x2192;</mo>
      </mrow>
    </math>
  </body>
</html>