Relatively or absolutely positioned body causes incorrect helper placement

As described in summary, a relatively or absolutely positioned body element will cause an offset for the helper, as shown in http://jsfiddle.net/bajG4/ . (And I am aware of the fact that setting the position of the body element in this way is - to say the very least - odd, but there are certain cases where this is quite useful). Personally I already solved this problem using an ugly help where I force the helper to position itself correctly and I attempted solving the underlining problem, but didn't have enough time.