/// <summary>
 /// Constructer for TeacherEditViewModel
 /// </summary>
 /// <param name="teacherData">The TeacherListItemViewData to Edit</param>
 public TeacherEditViewModel(TeacherListItemViewData teacherData)
     : base(teacherData)
 {
     addSubjectsToList();
     addClassesToList();
 }
        /// <summary>
        /// The methode EditTeacherCommand use to open a new edit window for the selected teacher
        /// </summary>
        /// <param name="teacher">The selected teacher</param>
        private void EditTeacher(TeacherListItemViewData teacher)
        {
            TeacherEditViewModel teacherEditViewModel = new TeacherEditViewModel(teacher);
            var editTeacher = new EditTeacher
            {
                DataContext = teacherEditViewModel
            };
            bool? didListChange = editTeacher.ShowDialog();

            if (didListChange == true)
            {
                addTeachersToPersons();
            }
        }