function PreloadImages()
{
    imgTitleWelcome = new Image(40, 200);
    imgTitleWelcome.src = "image/title-welcome.png";
    imgTitleAbout = new Image(40, 200);
    imgTitleAbout.src = "image/title-about.png";
    imgTitleAlbum = new Image(40, 200);
    imgTitleAlbum.src = "image/title-album.png";
    imgTitleAcknowledgments = new Image(40, 200);
    imgTitleAcknowledgments.src = "image/title-acknowledgments.png";
    imgWelcome = new Image (200, 140);
    imgWelcome.src = "image/button2-welcome.jpg";
    imgAbout = new Image (200, 140);
    imgAbout.src = "image/button2-about.jpg";
    imgAlbum = new Image (200, 140);
    imgAlbum.src = "image/button2-album.jpg";
    imgAcknowledgments = new Image (200, 140);
    imgAcknowledgments.src = "image/button2-acknowledgments.jpg";
}

function SwapDiv(div)
{
    document.getElementById('content-welcome').style.display = 'none';
    document.getElementById('content-about').style.display = 'none';
    document.getElementById('content-album').style.display = 'none';
    document.getElementById('content-acknowledgments').style.display = 'none';
    var id = div.id;
    switch (id) {
        case 'button-welcome':
            document.getElementById('content-welcome').style.display = 'block';
            document.getElementById('title').style.backgroundImage = 'url(image/title-welcome.png)';
            break;
        case 'button-about':
            document.getElementById('content-about').style.display = 'block';
            document.getElementById('title').style.backgroundImage = 'url(image/title-about.png)';
            break;
        case 'button-album':
            document.getElementById('content-album').style.display = 'block';
            document.getElementById('title').style.backgroundImage = 'url(image/title-album.png)';
            break;
        case 'button-acknowledgments':
            document.getElementById('content-acknowledgments').style.display = 'block';
            document.getElementById('title').style.backgroundImage = 'url(image/title-acknowledgments.png)';
            break;
    }
}