|| html.requestFullScreen || html.mozRequestFullScreen || html.webkitRequestFullScreen;
    if (requestFullscreen) {
      requestFullscreen.apply(html);
    }
  }

  Dz.setProgress = function(aIdx, aStep) {
    var slide = $("section:nth-of-type("+ aIdx +")");
    if (!slide)
      return;
    var steps = slide.$$('.incremental > *').length + 1,
        slideSize = 100 / (this.slides.length - 1),
        stepSize = slideSize / steps;
    this.progressBar.style.width = ((aIdx - 1) * slideSize + aStep * step