function logon() {
    var user = document.getElementById("user").value;
    var pass = document.getElementById("pass").value;

    if (user.length == 0) {
        alert("Please enter your email address");
        return;
    }
    if (pass.length == 0) {
        alert("Please enter a password");
        return;
    }

    document.getElementById("logon").submit();
}

function areaselect() {
    document.getElementById("areaselect").submit();
}

function logout() {
    document.getElementById("logoutform").submit();
}

function choose() {
    document.getElementById("intro").style.display = "none";
    document.getElementById("chooseintro").style.display = "block";
}

function newImage(arg) {
    if (document.images) {
        rslt = new Image();
        rslt.src = arg;
        return rslt;
    }
}

function changeImages() {
    if (document.images && (preloadFlag == true)) {
        for (var i=0; i<changeImages.arguments.length; i+=2) {
            document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
        }
    }
}

var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        navbar_03_over = newImage("images/menu/navbar_03-over.gif");
        navbar_04_over = newImage("images/menu/navbar_04-over.gif");
        navbar_05_over = newImage("images/menu/navbar_05-over.gif");
        navbar_06_over = newImage("images/menu/navbar_06-over.gif");
        navbar_07_over = newImage("images/menu/navbar_07-over.gif");
        navbar_08_over = newImage("images/menu/navbar_08-over.gif");

        nav_footer_01_over = newImage("images/nav_footer/nav_footer_01-over.gif");
        nav_footer_02_over = newImage("images/nav_footer/nav_footer_02-over.gif");
        nav_footer_03_over = newImage("images/nav_footer/nav_footer_03-over.gif");
        nav_footer_05_over = newImage("images/nav_footer/nav_footer_05-over.gif");

        preloadFlag = true;
    }
}