heh, it did work with +- at first but it felt finicky, I will ensure now the slider is in place that it works properly.
Also, I'll make sure its not so hidden - i only dropped it back in place last night and needed to see it was calculating properly.
I will clarify and ensure the interface works in due course


As for reverse order, its technically possible I just never saw the need for it - if enough people ask I'll drop it in but for now its not a priority in this release.