If you set this property to DrawModeEnum.OwnerDraw, the grid will fire the OwnerDrawCell event whenever a cell needs to be painted. You can handle the event and customize the way each cell is painted, either by changing the cell contents and style, or by taking over the painting and doing it yourself.

For more details and examples, see the OwnerDrawCell event.

Reference

C1FlexGridBase Class
C1FlexGridBase Members