anchor.diff:              let generalOptions = Setting.getGeneralOptions serviceProvider
               if generalOptions == null || not generalOptions.PeekDefinitionEnabled then null
               else
  -                match textDocumentFactoryService.TryGetTextDocument buffer with
  -                | true, doc ->
  -                    buffer.Properties.GetOrCreateSingletonProperty(
  -                        fun() -> 
  -                            upcast new PeekableItemSource(buffer, doc, peekResultFactory,
  -                                                          serviceProvider, projectFactory, vsLanguageService))
  -                | _ -> null+                let dte = serviceProvider.GetService<DTE, SDTE>()
  +                match VisualStudioVersion.fromDTEVersion dte.Version with
  +                | VisualStudioVersion.Unknown
  +                | VisualStudioVersion.VS2012
  +                | VisualStudioVersion.VS2013 -> null
  +                | _ ->
  +                    match textDocumentFactoryService.TryGetTextDocument buffer with
  +                    | true, doc ->
  +                        buffer.Properties.GetOrCreateSingletonProperty(
  +                            fun() -> 
  +                                upcast new PeekableItemSource(buffer, doc, peekResultFactory,
  +                                                              serviceProvider, projectFactory, vsLanguageService))
  +                    | _ -> null
positive.code: open FSharpVSPowerTools.ProjectSystem
  open Microsoft.FSharp.Compiler
  open Microsoft.FSharp.Compiler.SourceCodeServices
  
  type internal DefinitionPeekableItem(span: SnapshotSpan, range: Range.range, peekResultFactory: IPeekResultFactory) =
      interface IPeekableItem with
  
negative.code:         member __.Relationships = seq [PredefinedPeekRelationships.Definitions]
          member __.GetOrCreateResultSource _relationshipName = 
              { new IPeekResultSource with
                  member __.FindResults(relationshipName, resultCollection, _ct, _callback) =
                      if relationshipName <> PredefinedPeekRelationships.Definitions.Name then ()
                      else 
                          let filePath = range.FileName
  