anchor.diff:              member private x.CmdTabOrComplete () =
                   let mutable complete = false;
   
  -                if x.AutoCompleteEvent <> null then
  +                if x.AutoCompleteEvent.IsSome then
                       if x.TabAtStartCompletes then
                           complete <- true
                       else 
  
positive.code:                                 complete <- true
  
                      if complete then
                          let completion = x.AutoCompleteEvent.Invoke (text.ToString (), cursor)
                          let completions = completion.Result
                          if completions.Length <> 0 then
                              let ncompletions = completions.Length
  
negative.code: 
              /// Invoked when the user requests auto-completion using the tab character
              [<DefaultValue>]
              val mutable public AutoCompleteEvent : AutoCompleteHandler option
  
              let mutable handlers : Handler array = Array.zeroCreate 0
  
  