function showSubPageMenu(id, obj) {
  var menu = document.getElementById(id);

  if (obj != null) {
    objTemp = obj;
    if (objTemp.offsetParent) {
      menu_x = objTemp.offsetLeft;
      menu_y = objTemp.offsetTop;
      menu_w = objTemp.offsetWidth;
      menu_h = objTemp.offsetHeight;
      while (objTemp = objTemp.offsetParent) {
        menu_x += objTemp.offsetLeft;
        menu_y += objTemp.offsetTop;
      }
    }
  }

  menu.style.top = menu_y + menu_h + "px";
  menu.style.left = menu_x - ((menu.offsetWidth - menu_w) / 2) + "px";
  menu.style.visibility = "visible";
}

function hideSubPageMenu(id, obj) {
  var menu = document.getElementById(id);
  menu.style.visibility = "hidden";
}