i tried it and found the Free Nodelet Setting eat up the square brackets on js, so i patched it to work, as in Re^3: Free Nodelet freed.

here it is

<!-- the HTML: -->
Hide old replies: <input name="hide_old_replies"
id="hide_old_replies" type="checkbox" onClick="toggle_old_replies()" /
+>

<!-- the JS: -->
<script language="javascript"><!--

    function toggle_old_replies(){
      var chk = document.getElementById('hide_old_replies');
      var state = chk.checked ? 'none' : 'table-cell';
      var allelems = document.all ? document.all : document.getElement
+sByTagName("*");
      var inc = 0;
      for ( i = 0; i < allelems.length; i++ ) {
        var elem = eval("allelems\x5Bi]");
        if ( elem.className == "reply-body" ) {
          elem.style.display = state;
        }
      }
    }

//--></script>
[download]

Oha