var lastMenuItem;
function showSubMenu (id) {
  var domObj = document.getElementById(id);
  if (lastMenuItem) {
    lastMenuItem.style.display = "none";
    if (lastMenuItem == domObj) {
      lastMenuItem = null;
      return;
    }
  }
  if (lastSubMenuItem) lastSubMenuItem.style.display = "none";
  domObj.style.display = "block";
  lastMenuItem = domObj;
}
var lastSubMenuItem;
function showSecondSubMenu (id) {
  var domObj = document.getElementById(id);
  if (lastSubMenuItem) {
    lastSubMenuItem.style.display = "none";
    if (lastSubMenuItem == domObj) {
      lastSubMenuItem = null;
      return;
    }
  }
  domObj.style.display = "block";
  lastSubMenuItem = domObj;
}