>>The recordsource is a readwrite cursor, indexed on each column into a temp cdx.
>>
>>What could cause such a situation? I've never encountered a grid which wouldn't pass a proper columnOrder (which is not zero for any column, checked that too) to ARCC.
>
>Do you have any code in other grid's methods? Or did you bound anything to grid's methods?

The header1.rightclick was bound, but that wasn't it. I've found this line in the grid's init at the class level:

THIS.ALLOWCELLSELECTION=.F.

and that was the cause.