doingScrolling = 0;

function stopScrolling ( )
{
      doingScrolling = 0;
}

function doScrolling ( amount )
{
      if ( doingScrolling == 1 )
      {
            var scrollingPane = document.getElementById("thumbFrame");
            scrollingPane.contentWindow.scrollBy(amount, 0);
            setTimeout("doScrolling(" + amount + ")",10);
      }
}

function startScrolling ( amount )
{
      doingScrolling = 1;
      doScrolling( amount );
}