anchor.diff:              if i < tooltips.Length - 1 then
                   textBlock.Inlines.Add (LineBreak()))
                
  -        let tooltipBrushKey = box <| findColorResource "ToolTipBrushKey"
  +        findColorResource "ToolTipBrushKey"
  +        |> Option.iter (fun key -> textBlock.SetResourceReference(TextBlock.BackgroundProperty, key))
   
  -        if tooltipBrushKey <> null then
  -            textBlock.SetResourceReference(TextBlock.BackgroundProperty, tooltipBrushKey)
  -
  -        let tooltipTextBrushKey = box <| findColorResource "ToolTipTextBrushKey"
  -
  -        if tooltipTextBrushKey <> null then
  -            textBlock.SetResourceReference(TextBlock.ForegroundProperty, tooltipTextBrushKey);
  +        findColorResource "ToolTipTextBrushKey"
  +        |> Option.iter (fun key -> textBlock.SetResourceReference(TextBlock.ForegroundProperty, key))
   
           upcast textBlock
   
  
positive.code: //
  //    let docEventListener = new DocumentEventListener ([ViewChange.tagsEvent tagAggregator], 200us, update)
      
      let findColorResource name : obj =
          let assembly = 
              String.Format ("Microsoft.VisualStudio.Shell.{0}.0, Version={0}.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a", 12)
              |> Assembly.Load
  
          if assembly <> null then
              let ty = assembly.GetType "Microsoft.VisualStudio.PlatformUI.EnvironmentColors"
              let prop = ty.GetProperty name
              prop.GetValue(null, null)
          else null
  
      let createInfoText (tooltips: string list) : UIElement =
          let textBlock = TextBlock()
  
negative.code:                 | (span, _) :: _ ->
                      applicableToSpan <- buffer.CurrentSnapshot.CreateTrackingSpan (span.Span, SpanTrackingMode.EdgeExclusive)
                      res |> List.map snd |> createInfoText |> quickInfoContent.Add
          
          member x.Dispose(): unit = 
              if not disposed then
                  GC.SuppressFinalize x
                  disposed <- true
                  //(docEventListener :> IDisposable).Dispose()
  