private void buttonOk_Click(object sender, EventArgs e)
        {
            string errorMsg = "";

            if (textBoxPassword.Text != textBoxPasswordConfirm.Text)
                errorMsg = "Senhas não conferem";

            if (!String.IsNullOrEmpty(errorMsg))
            {
                ShowError(errorMsg);
                return;
            }

            try
            {
                Student student = new Student(this.textBoxNome.Text,
                                    this.textBoxSobrenome.Text,
                                    this.dateTimePickerNascimento.Value,
                                    new Email(this.textBoxEmailStudent.Text),
                                    new Email(this.textBoxEmailParent.Text),
                                    Int32.Parse(this.textBoxPassword.Text));

                ISession session = NHibernateHelper.OpenSession();
                StudentDAO studentDAO = new StudentDAO(session);
                studentDAO.Add(student);
                bSaved = true;
                session.Close();
                MessageBox.Show("Cadastro efetuado com sucesso!\n\nMatrícula: " + student.Id, "Cadastro");
                
                this.Close();
            }
            catch (Exception ex)    //at least one field with error
            {
                ShowError(ex.Message);
            }
        }