function swapTree(menuDiv, countTD)
{
   window.focus();
   for (j = menuDiv; j < menuDiv+countTD; j++) {
      d=eval("document.all.div"+j);
      i=eval("document.all.img_div"+menuDiv);
      if (d.style.display=="none")
      {
       d.style.display="block";
       i.src='images/minus.gif';
      } else {
       d.style.display="none";
       i.src='images/plus.gif';
      }
   }
}