this._oldAnnotation = null;

  this._Popcorn.listen("timeupdate", IriSP.wrap(this, this.timeUpdateHandler));

IriSP.ArrowWidget.prototype.timeUpdateHandler = function(percents) {

  var currentTime = this._Popcorn.currentTime();

  var currentAnnotation = this._serializer.currentAnnotations(currentTime)[0]; // FIXME : use the others ?

  /* move the arrow only if the current annotation changes */

  if (currentAnnotation != this._oldAnnotation) {

    var begin = (+ currentAnnotation.begin) / 1000;

    var end = (+ currentAnnotation.end) / 1000;

    var duration = +this._serializer.currentMedia().meta["dc:duration"] / 1000;

    var middle_time = (begin + end) / 2;

    var percents = Math.floor((middle_time / duration) * 100);

    // we need to apply a fix because the arrow has a certain length

    // it's half the length of the arrow (27 / 2). We need to convert

    // it in percents though.

    var totalWidth = this.selector.width();

    var correction = ((27 / 2) / totalWidth) * 100;

    var corrected_percents = percents - correction;

    this.selector.children(".Ldt-arrowWidget").animate({"left" : corrected_percents + "%"});

    this._oldAnnotation = currentAnnotation;

  }