anchor.diff:               define Entity.FillImage Assets.Default.Image9
                define Entity.BorderColor (Color (byte 0, byte 0, byte 0, byte 255))
                define Entity.BorderImage Assets.Default.Image12]
  -
  -        override this.Register (entity, world) =
  -            link (entity.ModelGeneric<single> ()) entity.Fill world
   
           override this.Actualize (entity, world) =
               if entity.GetVisible world then
  
positive.code:              define Entity.ToggleSoundVolume Constants.Audio.SoundVolumeDefault]
  
          override this.Register (entity, world) =
              let world = link (entity.ModelGeneric<bool> ()) entity.Toggled world
              let world = World.monitor handleMouseLeftDown Events.MouseLeftDown entity world
              let world = World.monitor handleMouseLeftUp Events.MouseLeftUp entity world
              world
  
negative.code:              define Entity.BackgroundImageOpt None
               define Entity.Justification (Justified (JustifyLeft, JustifyMiddle))]
  
          override this.Actualize (entity, world) =
              if entity.GetVisible world then
                  match entity.GetBackgroundImageOpt world with
  