anchor.diff:                       MessageBoxButtons.OK,
                        MessageBoxIcon.Error)
   
  -    let tryLoadFile fileName world =
  +    let tryLoadFile fileName (form : NuEditForm) world =
           try let world = World.removeGroupImmediate NuEditConstants.EditorGroupAddress world
               let (group, entities) = World.loadGroupFromFile fileName world
  -            World.addGroup NuEditConstants.EditorGroupAddress group entities world
  +            let world = World.addGroup NuEditConstants.EditorGroupAddress group entities world
  +            form.saveFileDialog.FileName <- Path.GetFileName fileName
  +            world
           with exn ->
               ignore <|
                   MessageBox.Show
  
positive.code:             | _ -> world)
  
      let handleSave (form : NuEditForm) (_ : WorldChangers) refWorld _ =
          form.saveFileDialog.FileName <- String.Empty
          let saveFileResult = form.saveFileDialog.ShowDialog form
          match saveFileResult with
          | DialogResult.OK -> trySaveFile form.saveFileDialog.FileName !refWorld
  
negative.code:         match openFileResult with
          | DialogResult.OK ->
              ignore <| worldChangers.AddLast (fun world ->
                  let world = tryLoadFile form.openFileDialog.FileName form world
                  let world = clearOtherWorlds world
                  form.propertyGrid.SelectedObject <- null
                  form.interactivityButton.Checked <- false
  