private void toolStripCustomers_Click(object sender, EventArgs e)
        {
            RentalReturnVideo frm = new RentalReturnVideo();

            frm.MdiParent = this;
            frm.Show();
        }
        private void issueReturnVideoToolStripMenuItem_Click(object sender, EventArgs e)
        {
            RentalReturnVideo frm = new RentalReturnVideo();

            frm.MdiParent = this;
            frm.Show();
        }