reraising a short all-in

[Meatmaw]

I'm hoping someone in B&M has some wisdom from the live games that they can impart on this rules issue (which we only partially resolved in 1-table-T). I was asking if a shortstack raises less than the minimum raise whether it was true that the original bettor could not reraise, and it was true apparently, but then the question came up on whether a limper can raise if said limper limps and a shortstack goes all in.

i.e.

Blinds 100/200, A limps, B goes all in with total stack of 300. Can A raise if everyone in front calls? I would think no, but apparently some claim that online the limper is allowed to (not claiming it's right, just that it happens).

Thanks.