function showSubMenu(sMenu) {    
    if (sMenu == 1) {
        document.getElementById("submenu").style.visibility="visible";
    } else {
        hideSubMenu();
    }
}
function hideSubMenu() {
    document.getElementById("submenu").style.visibility="hidden";
}
function selMenuAzz(menu) {
    document.getElementById(menu).className="titolo_azzurro";
}
function selMenuAra(menu) {
    document.getElementById(menu).className="titolo_arancio";
}
function selSubOpere(menu) {
    showSubMenu(1);
    document.getElementById(menu).className="selected";
}