click="MathJax.Menu.ShowSource.Text('POPUP CONTENT')" value="Open popup"/></li>
  </ul>
</li>
<li id="HTML-CSS">HTML-CSS:
  <ul>
    <li>LoadWebFont: <input type="button" onclick="MathJax.Message.Set(MathJax.Localization._(['HTML-CSS','LoadWebFont'],_M_,'FONTNAME'),null,null)" value="Show message box"/></li>
    <li>CantLoadWebFont: <input type="button" onclick="MathJax.Message.Set(MathJax.Localization._(['HTML-CSS','CantLoadWebFont'],_M_,'FONTNAME'),null,null)" value="Show message box"/></li>
    <li>Firef