If you go down to the last item, say while in the Multidrop menu, you can go further. Pressing left or right activates selection for the last item, but in order to go back up before the last item, you have to go up as many times as you went past the last item. If you go even further it goes back to the last item, with no percievable impact (presumably it’s hitting the last available slot for inventory, “overflowing”, then returning to the last possible menu choice)