function showSubMenu(menuItemCode, hoverImageUrl) {
    img = document.getElementById("img" + menuItemCode);
    if (img != null) {
        img.src = hoverImageUrl;
    }
    div = document.getElementById("div" + menuItemCode);
    if (div != null) {
        div.style.display = "block";
    }
}

function hideSubMenu(menuItemCode, imageUrl) {
    img = document.getElementById("img" + menuItemCode);
    if (img != null) {
        img.src = imageUrl;
    }
    div = document.getElementById("div" + menuItemCode);
    if (div != null) {
        div.style.display = "none";
    }
}