In een verkoop: ALT-T laat niet langer toe om tot een volgend stadium om te vormen

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using MercatorApi;
using MercatorUi;
using System.Windows.Forms;

namespace Billing
{
    public class Customizer : MercatorUi.ICustomizers.IFormLoadCustomizer, MercatorUi.ICustomizers.IFormClosedCustomizer
    {

        public void FormLoadCustomize(System.Windows.Forms.Form WindowsForm)
        {
            MercatorUi.Forms.Billing.BillingForm billingForm = (MercatorUi.Forms.Billing.BillingForm)WindowsForm;
            billingForm.KeyDown += new System.Windows.Forms.KeyEventHandler(billingForm_KeyDown);
        }

        public void FormClosedCustomize(System.Windows.Forms.Form WindowsForm)
        {
            MercatorUi.Forms.Billing.BillingForm billingForm = (MercatorUi.Forms.Billing.BillingForm)WindowsForm;
            billingForm.KeyDown -= new System.Windows.Forms.KeyEventHandler(billingForm_KeyDown);
        }

        void billingForm_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
        {
            MercatorUi.Forms.Billing.BillingForm billingForm = (MercatorUi.Forms.Billing.BillingForm)sender;
            if (e.Alt && (e.KeyCode == Keys.T) && billingForm.transformer.SubItems[0].Enabled)
            {
                billingForm.transformer.Focus();
                billingForm.BillingEngine.TransformUp();
            }
        }
    }
}