Identifying loaded rows in buffered paging

I have a grid that loads a few thousand rows, 100 at a time. I am also using the rowExpander plugin, In the past, when I used a paging bar at the bottom of my grid, I would just update the store with the new data url, and iterate over all of the rows in the store count, calling expand/toggle on each one.



How can I accomplish this using buffered paging, it seems that there isn't a grid refresh or similar event?



Thanks!