anchor.diff:                  if xty = typeof<System.TimeSpan> then 
                       model.Axes.Add (Axes.TimeSpanAxis(Position=pos))
                   if xty = typeof<string> then 
  -                    model.Axes.Add (Axes.CategoryAxis(Position=pos))
  +                    match gap with
  +                    | Some g -> 
  +                        let a = Axes.CategoryAxis(Position=pos)
  +                        a.GapWidth <- g
  +                        model.Axes.Add (a)
  +                    | _ -> model.Axes.Add (Axes.CategoryAxis(Position=pos))
               | _ -> ()
               ch)
   
  
positive.code:         /// <param name="Color">The color for the data.</param>
          /// <param name="XTitle">The title of the X-axis.</param>
          /// <param name="YTitle">The title of the Y-axis.</param>
          static member Column(data:seq<('key :> key)*#value>,?Name,?Title,?Labels, ?Color,?XTitle,?YTitle) = 
             GenericChart.Create(data |> listen |> mergeLabels Labels |> makeItems (fun ((k,v),labelOpt) -> ColumnItem(valueToDouble v)), ColumnSeries(ValueField="Value"))
               |> Helpers.ApplyStaticAxis(typeof<'key>, Axes.AxisPosition.Bottom)
               |> Helpers.ApplyStyles(?Name=Name,?Title=Title,?Color=Color,?AxisXTitle=XTitle,?AxisYTitle=YTitle)
  
          /// <summary>Uses a sequence of columns to compare values across categories.</summary>
  
negative.code:     type internal Helpers() = 
  
          /// Use a DateTime axis if the input key data is DateTime
          static member ApplyStaticAxis(xty, pos, ?gap) = (fun (ch:('T :> GenericChart)) -> 
              let model = ch.Model
              match model.DefaultXAxis with 
              | null -> 
  