defaultSpeed = 1; 
defaultFactor = 1;        
var bScrolling = false; 
var scrollspeed = 1;
var scrollfactor = 1;
function scroll_onMouseOver(dir)
{
    scrollspeed = defaultSpeed;
    scrollfactor = defaultFactor;
    if (dir == 'left')
        scrollspeed = -scrollspeed;

    bScrolling = true;
    continuous_scroll();           
}

function scroll_onMouseOut()
{
    bScrolling = false;
}

function scroll_onMouseDown()
{            
    scrollfactor = defaultFactor*10;
}

function scroll_onMouseUp()
{
    scrollfactor = defaultFactor;
}

function continuous_scroll()
{
    var tns_div = document.getElementById('id_thumbnails');

    tns_div.scrollLeft = tns_div.scrollLeft + (scrollspeed*scrollfactor);

    if ((tns_div.scrollLeft <= 0) || (tns_div.scrollLeft + tns_div.clientWidth >= tns_div.scrollWidth))
        bScrolling = false;
        
    if (bScrolling)
        setTimeout("continuous_scroll()", 10);
}

function reset_scroll()
{
    var tns_div = document.getElementById('id_thumbnails');
    tns_div.scrollLeft = 0;
}