anchor.diff:        SplashImageOpt : Image AssetTag option }
   
   /// Describes the shape of a desired overlay.
  -type [<StructuralEquality; StructuralComparison>] OverlayNameDescriptor =
  +type [<StructuralEquality; NoComparison>] OverlayNameDescriptor =
       | NoOverlay
       | RoutedOverlay
       | DefaultOverlay
  
positive.code: 
  /// The type of a screen transition. Incoming means a new screen is being shown, and Outgoing
  /// means an existing screen being hidden.
  type TransitionType =
      | Incoming
      | Outgoing
  
  /// The state of a screen's transition.
  type TransitionState =
      | IncomingState
      | OutgoingState
      | IdlingState
  
  /// Describes one of a screen's transition processes.
  type [<NoEquality; NoComparison; CLIMutable>] Transition =
      { TransitionType : TransitionType
        TransitionLifeTime : int64
  
negative.code: /// Specialized to Nu's specific use case by not providing a TryGetValue but rather ContainsKey and GetValue since Nu
  /// uses them separately. A more general implementation would only provide ToSeq and TryGetValue.
  type [<NoEquality; NoComparison>] MapGeneralized =
      { ToKeys : IComparable List
        ContainsKey : IComparable -> bool
        GetValue : IComparable -> obj }
  
  