anchor.diff:  /// A 2d render process that may or may not be threaded.
   type RenderProcess2d =
       interface
  +        abstract Started : bool
           abstract Terminated : bool
           abstract Start : unit -> unit
           abstract Submit : Vector2 -> Vector2 -> Vector2 -> RenderMessage2d List -> unit
  
positive.code:         abstract Terminate : unit -> unit
          end
  
  /// A threaded 2d render process.
  type RenderThread2d (createRenderer2d, window : Window) =
  
      let mutable taskOpt = null
      let terminatedLock = obj ()
      let mutable terminated = false
      let submissionLock = obj ()
  
negative.code: 
      interface RenderProcess2d with
  
          member this.Started =
              lock startedLock (fun () -> started)
  
          member this.Terminated =
              lock terminatedLock (fun () -> terminated)
  
  