PinchHandler needs a way to limit the actions it performs

PinchHander does 3 things: it manipulates rotation, scale and position. 

I think it would be good if there were a simple way to limit which of these actions is taken. There currently is a way of course by setting the target to null and then doing the operation manually, but that is not very declarative. For instance, if I wanted to make a two finger pinch only zoom, a three finger pinch rotate, and do dragging with a single finger only, I need manual connections for both needed PinchHandler instances.