protected virtual void HoursToTeach_button_Click(object sender, EventArgs e)
        {
            ChooseHoursToTeach form = new ChooseHoursToTeach(ref emp);

            this.Hide();
            form.FormClosed += new FormClosedEventHandler(FormClosedHandling);
            form.ShowDialog();
        }
        protected override void HoursToTeach_button_Click(object sender, EventArgs e)
        {
            EmpInterface       emp  = this.lecturer;
            ChooseHoursToTeach form = new ChooseHoursToTeach(ref emp);

            this.Hide();
            form.FormClosed += new FormClosedEventHandler(FormClosedHandling);
            form.ShowDialog();
        }