private void OnStart()
        {
            IsStarted = true;

            _grabber = ServiceLocator.Current.GetInstance <IGrabber>(SelectedSource.TypeName);
            _grabber.ProgressReport   += GrabberOnProgressReport;
            _grabber.ProgressChanged  += GrabberOnProgressChanged;
            _grabber.GrabbingFinished += GrabberOnGrabbingFinished;

            _grabber.StartAsync(new DirectoryCheckStrategy(_cacheFilePaths));
        }