ColumnEditor
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Expose the FlexGrid design-time column editor in your controls.

If you use the FlexGrid in UserControls and would like to allow users
to edit the grid columns using the design-time editor, your control must
implement the ISupportInitialize interface and forward the notifications
to the FlexGrid. This sample shows how to do it. 

To use the design-time column editor, open the form at design time, 
select the user control, and check the "GridColumns" property in the 
Property Window. Clicking the button next to the property value will 
open the FlexGrid's column editor which will allow you to customize 
the columns in the grid contained in the user control.