How to clean up event subscriptions added in a PlatformBehavior.OnAttachedTo

[DanTravison]

In my PlatformBehavior.OnAttachedTo, I'm subscribing to events on Window.Content but I cannot figure out how to remove these event subscribers.

I 'thought' that I could do it in PlatformBehavior.OnDetactedFrom but the bindable.Window.Handler has already been removed.

The docs indicate that OnDetachingFrom can be overridden but this is incorrect, since the method is sealed (?!).

I'm attaching the behavior to a ContentPage, in one case, the main page, in another a secondary page.

Thanks.