Not only the grid's filter, but also the order of rows and something other things.
Order it tricky, because sometimes the user will add new rows on top the grid's. They are not in any sorting order. But we still want to retain that order, keep the new added rows on top.
Basically, we don't want to refresh the nested grid when we .set the dataItem of the parent grid.
But if refreshing is inevitable, then at least I want to restore the filter and order.