function toggleVisibility(id, NNtype, IEtype, WC3type) {
    if (document.getElementById) {
        eval("document.getElementById(id).style.visibility = \"" + WC3type + "\"");
    } else {
        if (document.layers) {
            document.layers[id].visibility = NNtype;
        } else {
            if (document.all) {
                eval("document.all." + id + ".style.visibility = \"" + IEtype + "\"");
            }
        }
    }
}

function openMenu(expand_menu) {
    toggleVisibility('submenu1','hidden','hidden','hidden');
    toggleVisibility('submenu2','hidden','hidden','hidden');
    toggleVisibility(expand_menu,'show','visible','visible');
}

function closeMenu() {
    toggleVisibility('submenu1','hidden','hidden','hidden');
    toggleVisibility('submenu2','hidden','hidden','hidden');
}