gecko-dev/docshell/test/browser/file_bug1415918_beforeunloa...

<html>
<head>
  <style>
    body[fired] {
      background-color: #0f0;
    }
  </style>
  <script>
    window.onbeforeunload = function() {
      document.body.setAttribute("fired", true);
      return "Frame document prompt";
    }
  </script>
</head>
</body>
FRAME
</body>
</html>