Wayland 1.21 Released With New High Resolution Scroll Event
With Wayland 1.21, high-resolution wheel scrolling is added to the wl_pointer protocol via a new "wl_pointer.axis_v120" event for representing wheel detents as fractions or multiples of 120. The "120" approach is to match the behavior seen under Microsoft Windows.
The Linux 5.0 kernel and newer have supported high resolution scrolling, permitted it's also supported by the individual hardware driver. Libinput has already supported high resolution scrolling while this work opens it up to Wayland clients. Under X.Org, the xf86-input-libinput driver has already supported this more precise scrolling method. High resolution scrolling also remains open for XWayland, GNOME's Mutter, GTK, and other components.
In addition to the high-resolution wheel scrolling for wl_pointer, Wayland 1.21 adds has various convenience functions and different bug fixes -- mostly smaller items scattered throughout the code-base.
The brief Wayland 1.21 release announcement can be found on wayland-devel.