private void HallNewButton_Click(object sender, EventArgs e)
{
LectureHallForm form = new LectureHallForm();
form.SetHall(new LectureHall());
form.Show();
form.FormClosed += LectureHallForm_Closed;
}
private void HallEditButton_Click(object sender, EventArgs e)
{
LectureHallForm form = new LectureHallForm();
form.SetHall((LectureHall)HallCombobox.SelectedItem);
form.Show();
form.FormClosed += LectureHallForm_Closed;
}