var activeMenu;

function fnShowMenu(menuObj) {
  fnHideMenu();
  activeMenu = menuObj.lastChild;   // req. IE 5+
  activeMenu.style.visibility="visible";


  var left = menuObj.clientLeft - 2;
  var top = menuObj.clientTop + menuObj.offsetHeight;
  
  var debug = "left:: " + left + "\ntop:: " +  top + "\n"
  
  var oP =menuObj;
  var i=0;
  while (oP != null ) {
    debug += oP.tagName + ":  L " + oP.offsetLeft + " T " + oP.offsetTop + "\n";
    left += oP.offsetLeft;
    top += oP.offsetTop;
    oP = oP.offsetParent;
    i++;
  }
  
  //alert(debug);
  
  activeMenu.style.zIndex = 100;
  activeMenu.style.left = left;
  activeMenu.style.top = top;
  
}

function fnHideMenu() {
  if (!activeMenu) return;
  activeMenu.style.visibility="hidden";
  activeMenu.style.top = -1000;
  activeMenu = null;
  
}