Extends BaseView and adds additional awareness for selections, loading state, if the user is reloading, and contains utility and application level functions. Application functions proxy main application activity such as playing a video, or showing a screen.

• content the content that this screen loaded
• selection selection object for the currently selected content
• isLoading
• isUserChangePending
• NavController - reference to the NavController this screen belongs to - this is the navController that will be used for push, pop, and resetNavController

• getTopScreen - can be used to ask this screen what it considers its top view. This is useful if the screen in turn composes other screens (e.g. via nested NavControllers)
• push - pushes passed in screen to the navController
• pop - pops the current navController screen
• resetNavController - resets the navController - passing in a screen or index, will reset to that screen, or back to that index
• other utility functions implemented for your app

BaseScreen provides the same lifecycle methods as BaseView; but also provides

• getTopScreen - template method used by getTopScreen
• baseScreenOnShow - special hook used to overcome needing more onShow overrides (SceneGraph has a limit to super method calls)
• onUserChange - called when the user changes, so the view can update itself with the latest data