private void BtnEdit_Click(object sender, RoutedEventArgs e)
        {
            if (lbxCds.SelectedItem is Cd cdToEdit)
            {
                EditCdWindow editCdWindow = new EditCdWindow(cdToEdit);
                editCdWindow.ShowDialog();

                Repository repo = Repository.GetInstance();
                _cds = repo.GetAllCds();
                lbxCds.ItemsSource = _cds;
            }
            else
            {
                MessageBox.Show("Keine CD ausgewählt!");
            }
        }
        private void BtnEdit_Clicked(object sender, RoutedEventArgs e)
        {
            rep = Repository.GetInstance();
            Cd selectedCd = (Cd)lbxCds.SelectedItem;

            if (selectedCd != null)
            {
                EditCdWindow editCdWindow = new EditCdWindow(selectedCd);
                editCdWindow.ShowDialog();
            }
            else
            {
                MessageBox.Show("Wählen Sie eine CD zum Bearbeiten");
            }

            _cds = rep.GetAllCds();
            lbxCds.ItemsSource = _cds;
        }