var scrollTimer = null;

function moveup(scrolleeID)
    {
    var scrollee = document.getElementById(scrolleeID);
    scrollee.style.top = ((scrollee.offsetTop < -3)? scrollee.offsetTop + 3: 0) + 'px';
    }

function movedown(scrolleeID, scrollerID)
    {
    var scroller = document.getElementById(scrollerID);
    var scrollee = document.getElementById(scrolleeID);
    scrollee.style.top = (((scrollee.offsetTop + scrollee.offsetHeight) > scroller.offsetHeight)? scrollee.offsetTop - 3: scrollee.offsetTop) + 'px';
    }

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

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

function stop()
    {
    clearInterval(scrollTimer);
    }