gistfile1.js

// Click on track or labels
track.observe("mousedown", function(event) { 
  var element     = event.findElement(),
      steps       = {'pb-cat1': 0, 'pb-cat2': 6, 'pb-cat3': 13, 'pb-cat4': 24},
      localMouseX = event.pointerX() - track.viewportOffset().left,
      pos         = (localMouseX - slider.getWidth() / 2) / width * carousel.maxPos;
  if (element.id in steps) {
    carousel.goTo(steps[element.id] || pos);
  }
  else {
    carousel.goTo(pos, true);
    sliderMousedown(event);
  }
});