private void Button_Click(object sender, RoutedEventArgs e)
        {
            CostumersTable selected_costumer = (CostumersTable)CustomerSelectionComboBox.SelectedItem;

            CostumersBL.UpdateBL(selected_costumer, firstname_txb.Text, lastName_txb.Text, address_txb.Text, phone_txb.Text, mail_txb.Text, Int32.Parse(status_txb.Text), notes_txb.Text);
            this.Close();
        }
 private void Button_Click(object sender, RoutedEventArgs e)
 {
     CostumersBL.InsertBL(tb_firstName.Text, tb_lasrName.Text, tb_address.Text, tb_phone.Text, tb_mail.Text, 0, tb_notes.Text);
     this.Close();
 }