// customize the marquee var m = _flex.Marquee; m.Stroke = new SolidColorBrush(Colors.Red); m.Fill = new SolidColorBrush(Color.FromArgb(0x20, 0xff, 0x80, 0x80)); m.StrokeThickness = 4; m.RadiusX = 3; m.RadiusY = 3; // show the marquee _flex.ShowMarquee = true; // no need to highlight the selection/cursor _flex.SelectionBackground = null; _flex.CursorBackground = null;