protected override void editBtn_Click(object sender, EventArgs e)
        {
            _studentManager.SelectedRecord = (Student)listGridView.CurrentRow.DataBoundItem;

            AddEditStudentForm _editStudentForm = new AddEditStudentForm(_studentManager);

            _editStudentForm.Show();
        }
        protected override void addBtn_Click(object sender, EventArgs e)
        {
            _studentManager.SelectedRecord = null;

            AddEditStudentForm _addStudentForm = new AddEditStudentForm(_studentManager);

            _addStudentForm.Show();
        }