WIP: protocol: add wl_pointer's axis relative physical direction
This event adds the physical direction of the axis motion, relative to the axis event we get. Right now, when natural scrolling is enabled things like virtual volume sliders move the wrong way round.
By adding the axis motion direction, we can have toolkits swap the scroll direction for applicable widgets, getting the right behavior on all widgets.
cc @carlosg, @jadahl, iirc this was a GUADEC 2017 discussion
From patchwork
marking as WIP, shouldn't merge this until we have client-side implementation ready