function toggle_display_by_id(item_id)
{
   toggle_obj = document.getElementById(item_id);
   current_display_status = toggle_obj.style.display;
   if(current_display_status == 'none')
   {
      toggle_obj.style.display = '';
   }
   else
   {
      toggle_obj.style.display = 'none';
   }
}