private void ExecutePreviousWeekCommand()
        {
            CurrentSaterday = CurrentSaterday.AddDays(-7);

            FillCurrentWeekViewModel(CurrentSaterday);
//
//			OnPropertyChanged ("CurrentWeek");
        }
        private void ExecuteNextWeekCommand()
        {
            CurrentSaterday = CurrentSaterday.AddDays(7);

            FillCurrentWeekViewModel(CurrentSaterday);

            if (CurrentWeek.Count < 7)
            {
                // Add new Week
                AddNewWeek(CurrentSaterday.AddDays(CurrentWeek.Count), 7 - CurrentWeek.Count);

                FillCurrentWeekViewModel(CurrentSaterday);
            }
//
//			OnPropertyChanged ("CurrentWeek");
        }