anchor.diff:  
       let private getExpansionState (treeView : TreeView) =
           let nodeStates =
  -            Seq.fold
  -                (fun state (node : TreeNode) ->
  -                    if node.Nodes.Count = 0 then state
  -                    else (node.Name, node.IsExpanded) :: state)
  +            Seq.fold (fun state (node : TreeNode) ->
  +                if node.Nodes.Count = 0 then state
  +                else (node.Name, node.IsExpanded) :: state)
                   []
                   (enumerable treeView.Nodes)
           Map.ofSeq nodeStates
  
positive.code:         | _ -> ()
  
      let private refreshFormOnUndoRedo (form : GaiaForm) world =
          Globals.WorldRef := world
          form.tickingButton.Checked <- false
          refreshEntityPropertyGrid form world
          refreshLayerPropertyGrid form world
  
negative.code: // Copyright (C) Bryan Edds, 2013-2018.
  
  namespace Nu.Gaia
  open OpenTK
  open System
  open System.IO
  