anchor.diff:          /// Try to send a signal to a game.
           abstract TrySignal : obj * Game * World -> World
           default this.TrySignal (_, _, world) = world
  -    
  +
       /// The default dispatcher for screens.
       and ScreenDispatcher () =
           inherit SimulantDispatcher ()
  -    
  +
           /// Register a screen when adding it to the world.
           abstract Register : Screen * World -> World
           default this.Register (_, world) = world
  -    
  +
           /// Unregister a screen when removing it from the world.
           abstract Unregister : Screen * World -> World
           default this.Unregister (_, world) = world
  -    
  +
           /// Update a screen.
           abstract Update : Screen * World -> World
           default this.Update (_, world) = world
  -    
  +
           /// Post-update a screen.
           abstract PostUpdate : Screen * World -> World
           default this.PostUpdate (_, world) = world
  -    
  +
           /// Actualize a screen.
           abstract Actualize : Screen * World -> World
           default this.Actualize (_, world) = world
  -    
  +
           /// Try to get a calculated property with the given name.
           abstract TryGetCalculatedProperty : string * Screen * World -> Property option
           default this.TryGetCalculatedProperty (_, _, _) = None
  
positive.code:         /// Try to send a signal to a screen.
          abstract TrySignal : obj * Screen * World -> World
          default this.TrySignal (_, _, world) = world
      
      /// The default dispatcher for layers.
      and LayerDispatcher () =
          inherit SimulantDispatcher ()
      
          /// Register a layer when adding it to a screen.
          abstract Register : Layer * World -> World
          default this.Register (_, world) = world
      
          /// Unregister a layer when removing it from a screen.
          abstract Unregister : Layer * World -> World
          default this.Unregister (_, world) = world
      
          /// Update a layer.
          abstract Update : Layer * World -> World
          default this.Update (_, world) = world
      
          /// Post-update a layer.
          abstract PostUpdate : Layer * World -> World
          default this.PostUpdate (_, world) = world
      
          /// Actualize a layer.
          abstract Actualize : Layer * World -> World
          default this.Actualize (_, world) = world
      
          /// Try to get a calculated property with the given name.
          abstract TryGetCalculatedProperty : string * Layer * World -> Property option
          default this.TryGetCalculatedProperty (_, _, _) = None
  
negative.code: 
          interface SimulantState with
              member this.GetXtension () = this.Xtension
  
      /// Hosts the ongoing state of a screen. The end-user of this engine should never touch this
      /// type, and it's public _only_ to make [<CLIMutable>] work.
      /// NOTE: The properties here have duplicated representations in WorldModuleScreen that exist
  