Row selection currently flags each GridRow as selected. For paging, I might need to change it to keep an array of selected rows instead. Even if I did that, there would be possible errors because the selected row would not be in the rows collection.
The former implies that we get it as people scroll, but we don't have to discard what we already have - and eventually we could end up with everything held client side if they scroll for long enough. This is potentially easier to implement, and deals with some issues like "what if they selected some stuff on earlier pages"
The latter implies that we throw away what we had as they scroll, and go back to the server to get it again later if we need it - if you have a really big data set it makes sense, but otherwise it may be a lot harder for not a lot of benefit
(Note, I'm probably not a user of pagination, I just happened to read and think about it a bit, so thought I'd share my 5c despite having no dog in this fight)