scrollbar thing

gistfile1.txt

window.onscroll = function () {
    if (!docked && (menu.offsetTop - scrollTop() < 0)) {
        menu.style.top = 0;
        menu.style.position = 'fixed';
        menu.className = 'docked';
        docked = true;
    } else if (docked && scrollTop() <= init) {
        menu.style.position = 'absolute';
        menu.style.top = init + 'px';
        menu.className = menu.className.replace('docked', '');
        docked = false;
    }
};

function scrollTop() {
    return document.body.scrollTop || document.documentElement.scrollTop;
}