var navigationBarVisible = true;

function toggleNavigationBar() {
    if (navigationBarVisible) {
        hideNavigationBar();
    } else {
        showNavigationBar();
    }
}

function showNavigationBar() {
    var elm = document.getElementById("navigationBar");
    if (elm == null) return;
    elm.style.display = "block";

    var elm1 = document.getElementById("pageBorderTop");
    if (elm1 == null) return;
    elm1.style.display = "none";

    navigationBarVisible = true;
}

function hideNavigationBar() {
    var elm = document.getElementById("navigationBar");
    if (elm == null) return;
    elm.style.display = "none";

    var elm1 = document.getElementById("pageBorderTop");
    if (elm1 == null) return;
    elm1.style.display = "block";

    navigationBarVisible = false;
}