Support XInput2's smooth scrolling?

[anko]

The documentation around this is annoyingly thin, but to my understanding, XInput extension versions greater than 2 can fetch detailed scroll data. This allows smoother scrolling on touchpads, by exposing scrolled distances rather than individual ticks of the scroll wheel.

There's at least experimental support for XInput in XCB. Based on a superficial check, it's compiled into at least Arch's libxcb package. Where it isn't, configure-ing libxcb with --enable-xinput seems to do the trick.

Use cases:

• finer audio volume changer
• panning window managers

I tried to implement it, but got stuck very quickly. Maybe someone with better XCB chops could take a look?