var activeID=null;
hideTimer=setTimeout('',0);

function setSubmenu(id){
    clearTimeout(hideTimer);
    unsetSubmenu();		
    document.getElementById(id).style.display = 'block';
    activeID=id;
}

function unsetSubmenu() {
    if(activeID!=null){
        document.getElementById(activeID).style.display = 'none';
        activeID=null;
    }
}