var submenuId = null;

function showSubMenu(id) {
	//submenuId = id;
	if (document.getElementById(id).style.visibility == "visible") {
    document.getElementById(id).style.visibility="hidden";
  }
  else {
    document.getElementById(id).style.visibility="visible";
  }
}

function hideSubMenu(id) {
  if (document.getElementById(id).style.visibility == "visible") {
    document.getElementById(id).style.visibility="hidden";
  }
}