Alexandros Frantzis (@afrantzis) commented about dlls/winewayland.drv/wayland_pointer.c:
process_wayland.zwp_relative_pointer_manager_v1, pointer->wl_pointer); zwp_relative_pointer_v1_add_listener(pointer->zwp_relative_pointer_v1,
&relative_pointer_v1_listener, NULL);
&relative_pointer_v1_listener, &accum);
Let's place the accumulated x and y values in wayland_pointer, since it's really a per-pointer state (currently per-process since we have a single pointer).