private void PrintPreview()
        {
            Serienummers labels = ActiveMdiChild as Serienummers;

            if (labels != null)
            {
                labels.PrintPreview();
            }
        }
        private void LoadSerienummersForm(string path)
        {
            Serienummers serienummers = new Serienummers(path);

            if (serienummers.LoadSuccesful)
            {
                serienummers.MdiParent   = this;
                serienummers.FormClosed += new FormClosedEventHandler(labels_FormClosed);
                serienummers.Show();
            }
            else
            {
                serienummers.Dispose();
            }
        }