`swapWheelAxes` scrolling does not work consistently

[christopherbot]

When attempting to set swapWheelAxes to true, a few issues arise.

First, I'm finding that unless there is scrollable content in both the X and Y direction, scrolling in any direction is not registered.

When I do get it to generally work, sometimes only one direction within each axis scrolls and when a scroll handle reaches the end of its track, scrolling stops working all together (as if it gets locked into that position).