private void addGrade_MouseDown(object sender, MouseButtonEventArgs e) { AddGradeWindow addGrade = new AddGradeWindow(_student); addGrade.ShowDialog(); lvGrades.ItemsSource = _student.GradeList; this.AverageGrade.Text = string.Format("{0:F2}", _student.AverageGrade); this.TotalPoints.Text = _student.TotalPoints.ToString(); }