BCGControlBar Pro for MFC
virtual BOOL CBCGPGridCtrl::OnDropToGroupByBox ( int  )

Called by the framework when a header item (column) is dropped on the "group by" box.

Should return FALSE if the column can't be dropped on the "group by" box.

Override this function in a derived class and return FALSE when needed in order to disable dropping of certain items on the "group by" box.

The default implementation always returns TRUE.