private void btn_alert_Click(object sender, EventArgs e)
        {
            DueDateReminderCheckedOut reminder = new DueDateReminderCheckedOut();

            reminder.MdiParent = this.ParentForm;
            reminder.Show();
        }
        private void MDIChild_Load(object sender, EventArgs e)
        {
            DueDateReminderCheckedOut reminder = new DueDateReminderCheckedOut();

            reminder.MdiParent = this.ParentForm;
            reminder.Show();
        }