Comment 3 for bug 115153

So, has anyone had a chance to think about this? I've realized that it's
substantially more complicated than changing the way "sort by date" works, since
you just had to create a new "date" field used to sort the thread. Is sorting
by "order received" implemented as sorting by message number? Or sorting by
position in the stream? If the former, it's enough like "date" that the same
could be done.
Anyone know how it's implented currently, internally?