var menunow = null;
var submenunow = null;
var bgcolor_hilight = "#FFCC33";
var bgcolor_default = "#FFFF99";

function showmenu(id) {
  if (menunow != null) {
    hidemenu(menunow);
  }

  var obj = document.getElementById(id);

  obj.style.visibility = "visible";
  menunow = id;
}

function hidemenu(id) {
  var obj = document.getElementById(id);

  obj.style.visibility = "hidden";

  menunow = null;
}

function hilight_submenu(id) {
  if (submenunow != null) {
    unhilight_submenu(submenunow);
  }

  var obj = document.getElementById(id);

  obj.style.backgroundColor = bgcolor_hilight;

  submenunow = id;
}

function unhilight_submenu(id) {
  var obj = document.getElementById(id);

  obj.style.backgroundColor = bgcolor_default;

  submenunow = null;
}