hide = 0;
id = 0;

function menu(element) {
  i = 1; hide = 1;
  while (e = document.getElementById("m" + i++)) 
    e.style.visibility = "hidden";
  document.getElementById(element).style.visibility = "visible";
}

function end() {
  clearTimeout(id);
  hide=0; id = setTimeout(hidden, 20)
}

function hidden() {
  if (hide==0) {
    i = 1; 
    while (e = document.getElementById("m" + i++)) 
      e.style.visibility = "hidden";
  }
}