anchor.diff:                  sw :> Widget
   
           member x.GetToolbarWidgets() = List.empty<Widget> :> _
  -        member x.ReleaseOutlineWidget() = ()
  +
  +        member x.ReleaseOutlineWidget() =
  +            match treeView with
  +            | Some(treeView) -> let w = treeView.Parent :?> ScrolledWindow
  +                                w.Destroy()
  +                                treeView.Dispose()
  +            | None -> ()
  
positive.code:                 padTreeView.AppendColumn treeCol |> ignore
                  padTreeView.HeadersVisible <- true
                  padTreeView.Realized.Add(fun _ -> x.refillTree |> ignore)
                  padTreeView.Selection.Changed.Subscribe(fun _ -> jumpToDeclaration false) |> ignore
                  padTreeView.RowActivated.Subscribe(fun _ -> jumpToDeclaration true) |> ignore
  
                  let sw = new CompactScrolledWindow()
                  sw.Add padTreeView
  
negative.code:                     let renderer = cellRenderer :?> CellRendererText
                      let item = treeModel.GetValue(iter, 0) :?> FSharpNavigationDeclarationItem
                      renderer.Text <- item.Name
                  let jumpToDeclaration =
                      let iter : TreeIter ref = ref Unchecked.defaultof<_>
                      match padTreeView.Selection.GetSelected(iter) with
                      | true -> let node = padTreeView.Model.GetValue(!iter, 0) :?> FSharpNavigationDeclarationItem
  