private void BtnAddStudent_Click(object sender, EventArgs e)
{
FrmAddAndUpdateStudent addStuForm = new FrmAddAndUpdateStudent();
addStuForm.ShowDialog();
PopulateStudentListBox();
}
private void BtnUpdateStudent_Click(object sender, EventArgs e)
{
Student selectedStu = lstStudents.SelectedItem as Student;
var updateForm = new FrmAddAndUpdateStudent(selectedStu);
updateForm.ShowDialog();
PopulateStudentListBox();
}