public KanaChartViewModel(MainWindowViewModel mainWindowViewModel, IEnumerable <Kana> kanaList)
        {
            _mainWindowViewModel = mainWindowViewModel;
            _selectedKana        = new Observable <KanaChartItemViewModel>();
            Kana = kanaList.Select(k => new KanaChartItemViewModel(k));

            SelectedKana = Kana.FirstOrDefault();
        }