Fix the inline editor of the QMenuBar in Qt Designer not working
due to the key events being sent to the QMenu which is open
at that time.

Task-number: QTBUG-31059
Change-Id: Ic96bc119d0d2566d8f8d6ee62858445a70a447b7
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>