var scrollTimer = null;

function moveup(clip, scrolling)
    {
    var l = document.getElementById(scrolling);
    l.style.top = ((l.offsetTop < -5)? l.offsetTop + 5: 0) + 'px';
    }

function movedown(clip, scrolling)
    {
    var l = document.getElementById(scrolling);
    var p = document.getElementById(clip);
    l.style.top = (((l.offsetTop + l.offsetHeight) > p.offsetHeight)? l.offsetTop - 5: l.offsetTop) + 'px';
    }

function startmoveup(clip, scrolling)
    {
    if(scrollTimer)
        stop();
    scrollTimer = setInterval('window.moveup(\'' + clip + '\', \'' + scrolling + '\');', 20);
    }

function startmovedown(clip, scrolling)
    {
    if(scrollTimer)
        stop();
    scrollTimer = setInterval('window.movedown(\'' + clip + '\', \'' + scrolling + '\');', 20);
    }

function stop()
    {
    clearInterval(scrollTimer);
    }