private void addDiscipline_Click(object sender, RoutedEventArgs e)
        {
            TeacherDiscipline discipline        = null;
            Discipline        currentDiscipline = null;

            var editor = new DisciplineEditorWindow(_context, discipline, currentDiscipline);

            Hide();
            editor.ShowDialog();

            if (editor.DialogResult == true)
            {
                listDisciplines.ItemsSource = _context.TeacherDisciplines.ToList();
            }

            ShowDialog();
        }
        private void listDisciplines_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            if (listDisciplines.SelectedItem == null)
            {
                return;
            }

            var discipline        = listDisciplines.SelectedItem as TeacherDiscipline;
            var currentDiscipline = discipline.Discipline;

            var editor = new DisciplineEditorWindow(_context, discipline, currentDiscipline);

            Hide();
            editor.ShowDialog();

            if (editor.DialogResult == true)
            {
                listDisciplines.ItemsSource = _context.TeacherDisciplines.ToList();
            }

            ShowDialog();
        }