anchor.diff:          static member isSelectedScreenTransitioning world =
               not (World.isSelectedScreenIdling world)
   
  +        /// Set screen transition state, enabling or disabling input events respectively.
           static member private setScreenTransitionStatePlus state (screen : Screen) world =
               let world = screen.SetTransitionState state world
               match state with
  
positive.code:         static member relateGeneralized (address : obj Address) world =
              World.relate address world
  
          /// Try to check that the selected screen is idling; that is, neither transitioning in or
          /// out via another screen.
          [<FunctionBinding>]
  
negative.code:         [<FunctionBinding>]
          static member transitionScreen destination world =
              World.tryTransitionScreen destination world |> snd
  
          /// Set the splash aspects of a screen.
          [<FunctionBinding>]
  