Olivier Fourdan authored Oct 19, 2021 and Olivier Fourdan committed Oct 20, 2021

If the tablet tool is moved out of proximity before the cursor's pending
frame callback is received, any further attempts to update the cursor
will fail because the frame callback is still pending.

Make sure to clear any cursor pending frame when the tool gets in
proximity again, similar to what we do when the pointer re-enters a
surface, so that the cursor updates aren't discarded.
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
See-also: https://gitlab.gnome.org/GNOME/mutter/-/issues/1969

Reviewed-by: Carlos Garnacho <carlosg@gnome.org>