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

function mshow(id) {	
    mcancelclosetime();
    if(ddmenuitem)
        ddmenuitem.style.visibility = 'hidden';
    ddmenuitem = document.getElementById(id);
    ddmenuitem.style.visibility = 'visible';
}

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

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

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

document.onclick = mhide;