<!DOCTYPE html> <html class="reftest-wait"> <head> <title>munderover@accentunder</title> <meta charset="utf-8"/> <script type="text/javascript"> function doTest() { document.getElementById('mathOperator').setAttribute('accentunder', 'true'); document.documentElement.removeAttribute("class"); } window.addEventListener("MozReftestInvalidate",doTest, false); </script> </head> <body> <math> <munderover id="mathOperator"><mtext>X</mtext><mo>O</mo><mo>O</mo></munderover> </math> </body> </html>