Gets or sets a value that indicates whether the grid shows an Excel-style marquee around the current selection.
The code below shows how you can create a marquee with a thick rounded red border and semi-transparent red interior and use that to highlight the selection instead of the regular SelectionBackground and CursorBackground properties.
// 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;