function menu(id,img)
   {
      if(document.getElementById("3_"+id).style.visibility == "visible")
            {
               document.getElementById("3_"+id).style.visibility = "hidden";
               document.getElementById("3_"+id).style.position = "absolute";
               document.getElementById("img"+id).src="images/plus.png";
            }
         else
            {
               document.getElementById("3_"+id).style.visibility = "visible";
               document.getElementById("3_"+id).style.position = "static";
               document.getElementById("img"+id).src="images/minus.png";
            }
   }