Unbreak completion in text mode

Unbreak completion in text mode

Completion uses a complicated async scheme based on timers to update
itself. This is probably not necessary anymore and is fragile to
event order changes.

This is what happens with the new painting scheme. Therefore the
asyncHideXXX() methods have to be made more robust and detect whether
completion state has changed by the time they are triggered.

(cherry picked from commit f1ea7fee5cda3fbbeb9fdbb8bec2bd91c0745e56)