anchor.diff:            CreationTimeStamp : int64
             Xtension : Xtension
             Dispatcher : LayerDispatcher
  +          Depth : single
  +          Visible : bool
  +          Persistent : bool
             ScriptOpt : Symbol AssetTag option
             Script : Scripting.Expr array
             ScriptFrame : Scripting.DeclarationFrame
  
positive.code:           OnUnregister : Scripting.Expr
            OnUpdate : Scripting.Expr
            OnPostUpdate : Scripting.Expr
            OnSignal : Scripting.Expr
            TransitionState : TransitionState
            TransitionTicks : int64
            Incoming : Transition
            Outgoing : Transition
            Persistent : bool }
            
          /// Make a screen state value.
          static member make nameOpt (dispatcher : ScreenDispatcher) =
  
negative.code:               OnUnregister = Scripting.Unit
                OnUpdate = Scripting.Unit
                OnPostUpdate = Scripting.Unit
                OnSignal = Scripting.Unit }
  
          /// Try to get an xtension property and its type information.
          static member tryGetProperty propertyName layerState =
  