var current_submenu=null;
var timer=null;

function show_submenu(element) {
    hide_submenu();
    if (timer) {
        clearTimeout(timer);
        timer=null;
    }
    current_submenu=element.getElementsByTagName('div')[0];
    current_submenu.style.display='block';
}

function hide_submenu() {
    if (current_submenu) {
        current_submenu.style.display='none';
        current_submenu=null;
    }
}

function init_submenu_hide_timer() {
    timer=setTimeout(hide_submenu, 300);
}