var timeout = 500;
var closetimer = 0;
var ddmenuitem = 0;

function mopen(id) {	
  mcancelclosetime();

  if (ddmenuitem) {
    ddmenuitem.style.visibility = 'hidden';
  }

  ddmenuitem = document.getElementById(id);
  ddmenuitem.style.visibility = 'visible';
}

function mclose() {
  if (ddmenuitem) {
    ddmenuitem.style.visibility = 'hidden';
  }
}

function mclosetime() {
  closetimer = window.setTimeout(mclose,timeout);
}

function mcancelclosetime() {
  if (closetimer) {
    window.clearTimeout(closetimer);
    closetimer = null;
  }
}