var stopScroll = false;
var time_id;
var speedScroll = 30;
var pixelStep = 1;

function divScrollPlus()
{
  stopScroll = false;
  el = document.getElementById('f1');
  if (el) { el.scrollLeft = el.scrollLeft + pixelStep; }
  if (!stopScroll) { time_id = setTimeout("divScrollPlus()", speedScroll); }
}

function divScrollMinus()
{
  stopScroll = false;
  el = document.getElementById('f1');
  if (el) { el.scrollLeft = el.scrollLeft - pixelStep; }
  if (!stopScroll) { time_id = setTimeout("divScrollMinus()", speedScroll); }
}

function doStopScroll()
{
  clearTimeout(time_id);
  stopScroll = true;
}