protected NPointD TransformMousePositionToChartPoint(NMouseEventArgs e)
   {
    var view2Scale = new NViewToScale2DTransformation(this.cartesianChart, (int)StandardAxis.PrimaryX, (int)StandardAxis.PrimaryY);
    var scalePoint = new NVector2DD();
    view2Scale.Transform(new NPointF(e.X, e.Y), ref scalePoint);
    var transformedPoint = new NPointD();
    transformedPoint.X = scalePoint.X;
    transformedPoint.Y = scalePoint.Y;
    return transformedPoint;
   }