public TrckCtnrCtrl(ITrackableCtrl tracker)
        {
            InitializeComponent();

            if (tracker == null)
                throw new ArgumentNullException("tracker");

            _mTracker = tracker;
            this.xMainGrid.Children.Add(tracker.TrackableCtrl);
        }
 void IGrpPrgTracker.AddChildTracker(ITrackableCtrl tracker)
 {
     _mTrackableList.Add(tracker.Id, tracker);
 }