Since you're passing this as a parameter, you would have to include a parameter statement. In your particular case you don't actually have to pass a parameter (and therefore you would not need an lparameter statement), but it's a good practice to pass object reference in case you would need some special handling. So, I included it for general purpose. You may also check FAQ by Mike Helland: How to add code to grid's controls in run-time...

>>In order to use grid's DblClick event you would have to put code in Column's text DblClick event like this.parent.parent.DblClick(this)
>
>>In grid's DblClick you can do:
>lparameter toTextBox && not really needed, but just in case
>this.KeyValue = evaluate(this.ColumnHidden.ControlSource)
>
>>where you grid would have a custom property KeyValue and your hidden column always would have some predefined name...
>
>Perfect!
>I did have to include the lparameter toTextBox. Any idea why?
>
>Thank you,
>Tom