Don't preventDefault() for swipe movements orthogonal to scroller direction

[waldbaerkoch]

Consider a horizontal scroller (scrollingY: false) in a vertically scolllable page. Currently vertical swipe movements on the scroller will not trigger the native page scroll, because of
javascript rawEvent.preventDefault(); in _updateScroll.

For scrollers with scrollingY: false you could try to restrict rawEvent.preventDefault(); to only mainly horizontal swipe movements and correspondingly to mainly vertical swipes for scrollers with scrollingX: false.

[waldbaerkoch]

I think it's this:

                // Determine whether to prevent the default scroll event - if the scroll could still
                // be triggered, prevent the default to avoid problems (particularly on PlayBook)
                if (_instanceOptions.bouncing || scrollInterrupt || (_scrollableAxes.x && gesture.x && distancesBeyondBounds.x < 0) || (_scrollableAxes.y && gesture.y && distancesBeyondBounds.y < 0)) {
                    rawEvent.preventDefault();
                }

If you remove it and after

            // Update axes if appropriate
            for (axis in _scrollableAxes) {
                if (_scrollableAxes.hasOwnProperty(axis)) {
                    if (targetPositions[axis] > 0) {
                        targetPositions[axis] = _modifyDistanceBeyondBounds(targetPositions[axis], axis);
                    } else if (targetPositions[axis] < _metrics.scrollEnd[axis]) {
                        targetPositions[axis] = _metrics.scrollEnd[axis] + _modifyDistanceBeyondBounds(targetPositions[axis] - _metrics.scrollEnd[axis], axis);
                    }

                    if (_reqAnimationFrame) {
                        _animationTargetPosition[axis] = targetPositions[axis];
                    } else {
                        _setAxisPosition(axis, targetPositions[axis]);

add

if (Math.abs(targetPositions[axis]) > 10) {
    rawEvent.preventDefault();
}

it may work.