for (var i = 0; i < 7; i++) {
    (new Image()).src = getTopMenuImageUrl('topMenu' + i, true);
}

function toggleTopMenu(image, isOver) {
    changeTopMenuImage(image, isOver);
    var subMenuElement = $get(image.id + '_');
    set_visible(subMenuElement, isOver);
}

function toggleChildTopMenu(element, isOver) {
    set_visible(element, isOver);
    var id = element.id;var str = new String();
    var imageId = id.substr(0, id.length - 1);
    changeTopMenuImage($get(imageId), isOver);
}

function changeTopMenuImage(image, isOver) {
    image.src = getTopMenuImageUrl(image.id, isOver);
}

function getTopMenuImageUrl(name, isOver) {
    if (isOver) {
        name += '_';
    }
    return 'design/' + name + '.gif';
}

function showLeftChildMenu(sender, visible) {
    var subMenuElement = $get(sender.id + '_');
    set_visible(subMenuElement, visible);
}
function set_visible(element, value) {
    element.style.display = value ? '' : 'none';
}
function $get(id) {
    return document.getElementById(id);
}