private void group_info_button_Click(object sender, EventArgs e)
{
int id = int.Parse(id_of_lessonTextBox.Text);
DataView r = ((DataRowView)lessonsBindingSource[0]).DataView;
int index = r.Table.Rows[id - 1].Field <int>("Group");
group_formA group_FormA = new group_formA(index);
group_FormA.Show();
}
private void group_form_button_Click(object sender, EventArgs e)
{
group_formA gf = new group_formA();
gf.Show();
}