private void button3_Click(object sender, EventArgs e)
{
if (lbSubjects.SelectedItem != null)
{
QuestionAddForm form = new QuestionAddForm(((Subject)lbSubjects.SelectedItem).ID);
form.ShowDialog();
int selected = ((Subject)lbSubjects.SelectedItem).ID;
dgvQuestions.DataSource = null;
dgvQuestions.DataSource = controller.GetQuestions(selected);
}
}