Use "Locator.RegisterResolverCallbackChanged" to support switching the locator #59
Description
AppBuilder.UseReactiveUI uses
Locator.RegisterResolverCallbackChanged(() =>
This ensures, that the registration code is re-run in cases where the service locator is changed.
We use this to use Microsoft.Extensions.DependencyInjection.
In this line the locator is changed - so the registrations need to be rerun.