anchor.diff:              let world = World.publish4 () (SelectEventAddress ->>- screenAddress) screenAddress world
               (screen, world)
   
  +        /// Try to transition to the screen at the destination address if no other transition is in
  +        /// progress.
           static member tryTransitionScreen destinationAddress world =
               match World.getOptSelectedScreenAddress world with
               | Some selectedScreenAddress ->
  
positive.code:                 World.setSimulant simulant address world
              | None -> world
  
          static member updateOptSimulant updater address world =
              World.updateOptSimulantW (fun simulant _ -> updater simulant) address world
  
          static member updateByOptSimulant updater address world : World =
              match World.getOptSimulant address world with
              | Some simulant -> updater simulant world
              | None -> world
  
          static member updateSimulantW updater address world =
              let simulant = World.getSimulant address world
              let simulant = updater simulant world
              World.setSimulant simulant address world
  
          static member updateSimulant updater address world =
              World.updateSimulantW (fun simulant _ -> updater simulant) address world
  
          static member updateBySimulant updater address world : World =
              let simulant = World.getSimulant address world
              updater simulant world
  
          static member getOptSimulantForPublishingDefinition (address : Simulant Address) world =
              World.getOptSimulant address world
  
          static member tryGetIsSelectedScreenIdling world =
              match World.getOptSelectedScreen world with
              | Some selectedScreen -> Some <| Screen.isIdling selectedScreen
              | None -> None
  
          static member isSelectedScreenIdling world =
              match World.tryGetIsSelectedScreenIdling world with
              | Some answer -> answer
              | None -> failwith <| "Cannot query state of non-existent selected screen."
  
          static member tryGetIsSelectedScreenTransitioning world =
              Option.map not <| World.tryGetIsSelectedScreenIdling world
  
          static member isSelectedScreenTransitioning world =
              not <| World.isSelectedScreenIdling world
  
  
negative.code:             let world = World.monitor (World.handleAsScreenTransitionFromSplash destination) (OutgoingFinishEventAddress ->>- address) address world
              (splashScreen, world)
  
          /// Add a screen to the world at the given address that uses a dissolve transition.
          static member addDissolveScreen persistent dissolveData dispatcherName address world =
              let dissolveScreen = { World.makeDissolveScreen dissolveData dispatcherName (Some <| Address.head address) world with Persistent = persistent }
              let dissolveScreenHierarchy = (dissolveScreen, Map.empty)
              World.addScreen dissolveScreenHierarchy address world
  
          /// Add a dissolve screen to the world at the given address whose contents is loaded from
          /// the given group file.
          static member addDissolveScreenFromGroupFile persistent dissolveData dispatcherName groupFilePath address world =
              let dissolveScreen = { World.makeDissolveScreen dissolveData dispatcherName (Some <| Address.head address) world with Persistent = persistent }
              let (group, entities) = World.readGroupHierarchyFromFile groupFilePath world
  