/// <summary>
        /// Open a existing Customer List or create a new one, and give it focus.
        /// </summary>
        private void ClickNewCustomerList(object sender, EventArgs e)
        {
            // Get the current instance of the CustomerEntry form or create a new one if not there
            formCustomerEntry customerList = formCustomerEntry.Instance;

            // Assign it's MDI parent to be the form this event was called in
            customerList.MdiParent = this;

            // Dispaly the form and give focus
            customerList.Show();
            customerList.Focus();
        }
 /// <summary>
 /// When the form is closed release the instance.
 /// </summary>
 private void CustomerFormClosed(object sender, FormClosedEventArgs e)
 {
     instance = null;
 }