function formuoti_pranesima(klaidos) {
    if (klaidos.length==1) 
        pranesimas = "Klaida!\n"+klaidos[0]+".";
    else {
        pranesimas = "Klaidos!"; 
        for (i=1; i<=klaidos.length; i++)
           pranesimas += "\n"+i+". "+klaidos[i-1]+".";
    }
    return pranesimas;
}

var active_menu_id = 0;

function show_submenu(menu_id) {
    if (el = document.getElementById('submenu_'+active_menu_id)) {
        el.className = "submenu";
    }
    
    if (el = document.getElementById('submenu_'+menu_id)) { 
        el.style.visibility = "visible";
    }
    
    el = document.getElementById('menu_item_'+menu_id);
    el.className = "menu_item active_menu_item";
}

function hide_submenu(menu_id) {
    if (el = document.getElementById('submenu_'+menu_id)) {
        el.style.visibility = "hidden";
    }
    
    el = document.getElementById('menu_item_'+menu_id);
    el.className = "menu_item";
    
    if ((el = document.getElementById('submenu_'+active_menu_id))) { //&& (document.getElementById('active_submenu'))) {
        el.className = "submenu allways_expanded";
    }
}