var activeMenu;

if (document.layers) {
  document.layers['Top'].captureEvents(Event.MOUSEOVER);
  document.layers['Top'].onmouseover=hideMenu;
  document.layers['Main'].captureEvents(Event.MOUSEOVER);
  document.layers['Main'].onmouseover=hideMenu;
  document.layers['Menu01'].captureEvents(Event.MOUSEOVER);
  document.layers['Menu01'].onmouseover=showMenu01;
  document.layers['Menu02'].captureEvents(Event.MOUSEOVER);
  document.layers['Menu02'].onmouseover=showMenu02;
  document.layers['Menu03'].captureEvents(Event.MOUSEOVER);
  document.layers['Menu03'].onmouseover=hideMenu;
  document.layers['Menu04'].captureEvents(Event.MOUSEOVER);
  document.layers['Menu04'].onmouseover=showMenu04;
}

function hideMenu() {
  if (activeMenu != null) {
    if (document.all) {
      document.all[activeMenu].style.visibility = "hidden";
    } else if (document.layers) {
      document.layers[activeMenu].visibility = "hide";
    }
    activeMenu = null;
  }
}
function showMenu01()
{
  hideMenu();
  if (document.all) {
    document.all['SubMenu01'].style.visibility = "visible";
  } else if (document.layers) {
   document.layers['SubMenu01'].visibility = "show";
  }
  activeMenu = "SubMenu01";
}
function showMenu02()
{
  hideMenu();
  if (document.all) {
    document.all['SubMenu02'].style.visibility = "visible";
  } else if (document.layers) {
   document.layers['SubMenu02'].visibility = "show";
  }
  activeMenu = "SubMenu02";
}
function showMenu04()
{
  hideMenu();
  if (document.all) {
    document.all['SubMenu04'].style.visibility = "visible";
  } else if (document.layers) {
   document.layers['SubMenu04'].visibility = "show";
  }
  activeMenu = "SubMenu04";
}