如何解决IE6的z-index错误?

我读过这个 iFrame workaround IE6。

我附上了一个样品。 (应显示在选择控件上)

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Test</title>

  <script type="text/javascript">
    function showItem(obj) {
      obj.style.visibility = 'visible';
      obj.focus();
    }
  </script>

</head>
<body>
  <input onclick="showItem(myPanel)" />
  <div id="myPanel" style="position: absolute; top: 35px; left: 10px; width: 200px;
    height: 200px; background-color: Gray; visibility: hidden; color: Silver;">
    Hello world
  </div>
  <div>
    <select name="thisDD" id="thisDD">
      <option value="1">One</option>
      <option value="2">Two</option>
      <option value="3">Three</option>
    </select>
  </div>
</body>
</html>