function toggleLayer( id_closed, id_open )
{
    if (document.getElementById)
    {
      obj = document.getElementById(id_open);
      if (obj.className.match("hidden"))
      {
        if(obj.className.match("hidden"))
        {
          obj.className =  obj.className.replace("hidden", "");
        }
       
        obj_two = document.getElementById(id_closed);
        obj_two.className = obj_two.className + " hidden ";
      }
    }
}