anchor.diff:                  fileName <- newfileName
                   (source :> IdealSource).RecolorizeWholeFile()
   
  -#if DEBUG        
  -        override source.OriginalFilename = originalFilename
  -#endif
  -
           // Just forward to IdealSource  
           interface IdealSource with
               member source.RecolorizeWholeFile() = source.IdealSource.RecolorizeWholeFile() 
  
positive.code:         let mutable filechange = filechange
          let mutable textLines = textLines
  
  #if DEBUG        
          let originalFilename = VsTextLines.GetFilename textLines
  #endif
          let mutable fileName = VsTextLines.GetFilename textLines
  
  
  
negative.code: 
      // Can't untangle from MLS Source. The purpose of this class is to 
      // satisfy the requirement of inheriting from Source. 
      type internal SourceOverIdealSource(service:LanguageService, textLines, colorizer, filechange:IVsFileChangeEx) = 
          inherit SourceImpl(service, textLines, colorizer)
          
  