private void drawAllCueArrows(DrawingContext dc)
        {
            CuePointDisplay cuePointDisplay = (CuePointDisplay)Target;

            double pw = cuePointDisplay.PointerWidth,
                w = cuePointDisplay.ActualWidth;

            foreach (var cuePoint in cuePointDisplay.CuePoints)
            {
                double x = cuePointDisplay.GetPercentage(cuePoint) / 100 * w;

                dc.DrawGeometry(new SolidColorBrush(cuePoint.Color), new Pen(), getCueArrow(pw, x));
            }
        }
        protected override Geometry GetControlShape()
        {
            CuePointDisplay cuePointDisplay = (CuePointDisplay)Target;

            return new RectangleGeometry(new Rect(0, 0, cuePointDisplay.ActualWidth, cuePointDisplay.ActualHeight));
        }