private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            StudentData cntx = new StudentData();

            cntx.TestStudentsIfEmpty();
            // MessageBox.Show(cntx.ToString());
        }
        public MainWindow()
        {
            InitializeComponent();
            FillStudStatusChoices();

            if (GradesData.TestGradesEmpty() == true)
            {
                GradesData.CopyTestGrades();
            }


            if (StudentData.TestStudentsIfEmpty() == true)
            {
                StudentData.CopyTestStudents();
            }
        }