Listidentifies rows byariaAttributes(specificallyaria-posinset) so that additional children (e.g. sticky rows or overlays) aren't measured as rows, and rows that render nothing don't shift the indices of the rows after them. Rows that don't spreadariaAttributes, or that overridearia-posinsetoraria-setsize, are still matched by their position. If only some rows spreadariaAttributes(e.g. loaded rows but not loading placeholders), the rows that don't are not measured; spreadariaAttributesonto every row (or none). - #930, #931