ToastNotifications change target window?

Question

C++ / C#

I am using Nuget - ToastNotifications.
How to specify in "parentWindow" another, not the main window? Thank you.

Notifier notifier = new Notifier(cfg =>
        {
            cfg.PositionProvider = new WindowPositionProvider(
                parentWindow: Application.Current.MainWindow,
                corner: Corner.TopRight,
                offsetX: 10,
                offsetY: 10);

            cfg.LifetimeSupervisor = new TimeAndCountBasedLifetimeSupervisor(
                notificationLifetime: TimeSpan.FromSeconds(3),
                maximumNotificationCount: MaximumNotificationCount.FromCount(5));

            cfg.Dispatcher = Application.Current.Dispatcher;
        });