>I tryed your suggestion as a new class, can not get the class into the column visually.
> error "Can not add this object to grid". I have the grid in edit mode and correct column in properties box.
>
>I put the code, corrected, into the checkbox.refresh already there, and does not work.

Strange, why wouldn't you be able to add an object to the grid's column? Try to do it programmatically then.

BTW, the error indicates that you were trying to add this checkbox to the grid itself, not the column. I'm not sure how does it happen. Try to do it again...