Code review comment for lp://staging/~ilidrissi.amine/gesturetest/621600-no-args

I'll give an example that caused us issues. If you want to perform a rotation where one finger pivots around another, you will receive both rotation and drag events. The reason is that gestures are performed about a point in space. Our gesture system uses the center (average) of all the touch points as this "focus" point. So if you perform a pivot rotation, you'll see the focus point being rotated, but you'll also see it being dragged. This is the correct behavior, but it isn't obvious.

We had a bug filed against our recognizer where the user didn't expect to see drag events when performing a pivot rotation. What they should have done is subscribed to just the rotate gesture events, since all they cared about was the rotation. I don't want to lead people to assume our stack is broken because they ran gesturetest without any arguments and saw behavior they didn't understand. Thus, I want to keep the functionality as is, potentially requiring the user to read the man page to understand what gesturetest is really doing.