public App()
{
// Push the knowledge about connecting and instantiating view and viewmodel to a 3rd party/component.
IEventAggregator eventAggregator = new EventAggregator(Current.Dispatcher);
IPresentationManager manager = new PresentationManager();
manager.Register<DialogView, DialogViewModel>();
manager.Register<MainView, MainViewModel>();
var mainViewModel = new MainViewModel(manager, eventAggregator);
manager.ShowViewFor(mainViewModel);
}