anchor.diff:          member this.ClickSound with get () = this?ClickSound () : Sound
           member this.SetClickSound (value : Sound) : Entity = this?ClickSound <- value
   
  -        // label
  +        (* label xfields *)
           member this.LabelSprite with get () = this?LabelSprite () : Sprite
           member this.SetLabelSprite (value : Sprite) : Entity = this?LabelSprite <- value
   
  -        // text box
  +        (* text box xfields *)
           member this.BoxSprite with get () = this?BoxSprite () : Sprite
           member this.SetBoxSprite (value : Sprite) : Entity = this?BoxSprite <- value
           member this.Text with get () = this?Text () : string
  
positive.code:         member this.ToggleSound with get () = this?ToggleSound () : Sound
          member this.SetToggleSound (value : Sound) : Entity = this?ToggleSound <- value
  
          // feeler
          member this.IsTouched with get () = this?IsTouched () : bool
          member this.SetIsTouched (value : bool) : Entity = this?IsTouched <- value
  
          // block
          member this.PhysicsId with get () = this?PhysicsId () : PhysicsId
          member this.SetPhysicsId (value : PhysicsId) : Entity = this?PhysicsId <- value
          member this.Density with get () = this?Density () : single
  
negative.code: 
      type Entity with
          
          (* button xfields *)
          member this.IsDown with get () = this?IsDown () : bool
          member this.SetIsDown (value : bool) : Entity = this?IsDown <- value
          member this.UpSprite with get () = this?UpSprite () : Sprite
  