anchor.diff:              | _ -> 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
  
positive.code:                      MessageBoxButtons.OK,
                       MessageBoxIcon.Error)
  
      let tryLoadFile fileName world =
          try let world = World.removeGroupImmediate NuEditConstants.EditorGroupAddress world
              let (group, entities) = World.loadGroupFromFile fileName world
              World.addGroup NuEditConstants.EditorGroupAddress group entities world
          with exn ->
              ignore <|
                  MessageBox.Show
  
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
  