private void Button_NewCustomer_Click(object sender, RoutedEventArgs e)
{
Window_NewCustomer window = new Window_NewCustomer();
window.Closed += OnClose;
window.ShowDialog();
}
private void AddCustomer(object sender, RoutedEventArgs e)
{
Window_NewCustomer window = new Window_NewCustomer(gridCustomers);
window.ShowDialog();
}