This way, when changing focus between outputs, the directional focus
command will focus the focused window within the parent container that
is next in the given direction.
Previously, the next window of the given direction was focused which is
Inconsistent with changing focus inside the same output.
Fixes#1160.
To be honest, I’m not entirely sure where the race condition originates
from, but when making sure that there are no pending events
(which is what sync_with_i3 accomplishes) before warping the pointer, we
have less flaky testsuite runs.
closes#1189