void DayDoubleClicked_Manager(Object data)
        {
            ScheduleDay day = data as ScheduleDay;
            EditScheduleWindow w = new EditScheduleWindow();
            w.ShowWithScheduleDay(day, this.groupList.SelectedItem as studentsgroup, this.timeTable.FirstDay);

            this.timeTable.FillTable(DBModel.Instance.GetLessonsByPeriodAndRef(this.lessonCollection, this.timeTable.FirstDay, this.timeTable.FirstDay.AddDays(14)));

        }
        void EditSchedule(Object data)
        {
            EditScheduleWindow w = new EditScheduleWindow();
            w.ShowDefault(this.groupList.SelectedItem as studentsgroup, this.timeTable.FirstDay);

            
            this.timeTable.FillTable(DBModel.Instance.GetLessonsByPeriodAndRef(this.lessonCollection, this.timeTable.FirstDay, this.timeTable.FirstDay.AddDays(14)));
        }