function mainover(div_id)
  {
  var elemt = document.getElementById(div_id);
  if (elemt.style.display != "block")
    {
    elemt.style.display = "block";
    }
  disableOthers(elemt,div_id);
  }
function disableOthers(elemt,div_id)
  {
  var subMenuDivArray = elemt.parentNode.getElementsByTagName("div");
  for (var i=0;i<subMenuDivArray.length;i++)
    {
    var divElemt = subMenuDivArray[i];
    if (divElemt.id != '')
      {
      if (divElemt.id != div_id)
        {
        divElemt.style.display = "none";
        }
      }
    }
  }