Otherwise it's possible that a keystroke is sent in for a different view,
when that other view reacts to an invalidation (invoking paintTile())
caused by a previous keystroke.

I.e. open two views, place the cursor at different positions, type fast,
and some of the characters appeared at the incorrect view.

Change-Id: Ie5e471f1b9c2d69adaa87111fba74d4abe184ef8
Reviewed-on: https://gerrit.libreoffice.org/26562Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>