anchor.diff:          /// you may be wanting to use the higher-level World.transitionScreen function instead.
           [<FunctionBinding>]
           static member setSelectedScreenOpt value world =
  -            World.updateGameState (fun layerState -> { layerState with SelectedScreenOpt = value }) Property? SelectedScreenOpt world
  +            if Option.isSome value && World.getOmniscreenOpt world = value then failwith "Cannot set SelectedScreen to Omniscreen."
  +            World.updateGameState (fun gameState -> { gameState with SelectedScreenOpt = value }) Property? SelectedScreenOpt world
   
           /// Get the currently selected screen (failing with an exception if there isn't one).
           [<FunctionBinding>]
  
positive.code:         /// Set the omniscreen or None.
          [<FunctionBinding>]
          static member setOmniscreenOpt value world =
              World.updateGameState (fun layerState -> { layerState with OmniscreenOpt = value }) Property? OmniscreenOpt world
  
          /// Get the omniscreen (failing with an exception if there isn't one).
          [<FunctionBinding>]
  
negative.code:         /// Set the current eye center.
          [<FunctionBinding>]
          static member setEyeCenter value world =
              World.updateGameState (fun gameState -> { gameState with EyeCenter = value }) Property? EyeCenter world
  
          /// Get the current eye size.
          [<FunctionBinding>]
  