private void AddCustomer()
        {
            if (window == null)
            {
                MusteriModel musteri = new MusteriModel();

                window = new AddCustomerWindow(musteri);

                window.AddCustomerViewModel.PersonelSave += AddCustomerViewModelSaved;
                window.Closing += AddCustomerWindowClosing;
                window.Show();
            }

            else
            {
                window.Focus();
            }
        }
 private void AddKlantWindow()
 {
     _addCustomerWindow       = new AddCustomerWindow();
     _addCustomerWindow.Owner = Application.Current.MainWindow;
     _addCustomerWindow.Show();
 }