   }
    if (newstep != this.step) {
      this.setIncremental(newstep);
    }
    for (var i = 0; i < this.remoteWindows.length; i++) {
      this.postMsg(this.remoteWindows[i], "CURSOR", this.idx + "." + this.step);
    }
  }

  Dz.back = function() {
    if (this.idx == 1 && this.step == 0) {
      return;
    }
    if (this.step == 0) {
      this.setCursor(this.idx - 1,
                     this.slides[this.idx - 2].$$('.incremental > *').length);
    } else {
      this.setCursor(this.idx, this.step -