var scrolltimer = 0;

function clearScroll() { window.clearTimeout(scrolltimer); }

function scroll(p, o, dir) {
    var tmp = Math.max(-document.getElementById(o).scrollHeight + document.getElementById(p).clientHeight, Math.min((parseInt(document.getElementById(o).style.top) + (2 * dir)), 0));
    if (isNaN(tmp)) { tmp = 0; }
    document.getElementById(o).style.top = tmp + 'px';
    what = (dir > 0 ? 'scrollUp( \'' + p + '\', \'' + o + '\' )' : 'scrollDown( \'' + p + '\', \'' + o + '\' )');
    scrolltimer = setTimeout(what, 10);
    return false;
}

function scrollUp(p, o) { return scroll(p, o, 1); }
function scrollDown(p, o) { return scroll(p, o, -1); }