Scroll listener - first distanceY always negative for downward scroll?
<p>I've got a GestureDetector.OnGestureListener hooked up to a ListView. I'm trying to listen for scroll events when the user is scrolling down:</p>

<pre><code>private GestureDetector.OnGestureListener mOnGesture = new GestureDetector.OnGestureListener() {
    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
    }
}
</code></pre>

<p>But I see a very strange stream of "distanceY" values:</p>

<pre><code>distanceY: -417.02252  // &lt;-- huh?
e1: null
e2: MotionEvent{4097ac08 action=2 x=233.6657 y=417.02252 pressure=0.79999995 size=0.33333334}

distanceY: 1.5640259
e1: null
e2: MotionEvent{4097ac08 action=2 x=233.6657 y=415.4585 pressure=0.79999995 size=0.33333334}

distanceY: 1.5640259
e1: null
e2: MotionEvent{4097ac08 action=2 x=233.6657 y=413.89447 pressure=0.79999995 size=0.40000004}

... rest of values are positive, as expected ...
</code></pre>

<p>The first "distanceY" value is negative (unexpected), but then subsequent ones are all positive. What could explain this? I can reproduce this behavior each time. </p>

<p>Thanks</p>
