userAgent = window.navigator.userAgent;
browserVers = parseInt(userAgent.charAt(userAgent.indexOf("/")+1),10);
function newImage(arg) {
    if (document.images) {
        rslt = new Image();
        rslt.src = arg;
        return rslt;
    }
}

function findElement(n,ly) {
    if (browserVers < 4)		return document[n];
    var curDoc = ly ? ly.document : document;
    var elem = curDoc[n];
    if (!elem) {
        for (var i=0;i<curDoc.layers.length;i++) {
            elem = findElement(n,curDoc.layers[i]);
            if (elem) return elem;
        }
    }
    return elem;
}

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

var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        nbl_home_over = newImage("images/nbl_home-over.jpg");
        day1_over = newImage("images/day1-over.jpg");
        day2_over = newImage("images/day2-over.jpg");
        day3_over = newImage("images/day3-over.jpg");
        day4_over = newImage("images/day4-over.jpg");
        day5_over = newImage("images/day5-over.jpg");
        day6_over = newImage("images/day6-over.jpg");
        day7_over = newImage("images/day7-over.jpg");
        day8_over = newImage("images/day8-over.jpg");
        day9_over = newImage("images/day9-over.jpg");
        day10_over = newImage("images/day10-over.jpg");
        map_over = newImage("images/map-over.jpg");
        photos_over = newImage("images/photos-over.jpg");
        lessons_over = newImage("images/lessons-over.jpg");
        jungle_over = newImage("images/jungle-over.jpg");
        preloadFlag = true;
    }
}