code: function draw(attrsModified) {
      calc();
      if (isChanged && value != prevValue)
        slider.dispatchEvent(onChange);
      isChanged = false;
      if (!attrsModified && value == prevValue)
        return;
      prevValue = value;
      var position = range ? (value - min) / range * 100 : 0;
      var bg = '-moz-element(#__sliderthumb__) ' + position + '% no-repeat, ';
      style(slider, { background: bg + track });
    }
docs: renders slider using CSS background ;)