Fix display sometimes randomly scrolling down
Something in Qt has changed, so e. g. Super_L isn't passed as a modifier anymore, so there's a regression from what eea5ecfc fixed.
This is especially annoying e. g. for people using i3, where just switching focus away with the keyboard will lead to Konsole scrolling back to the bottom.
Moved from https://phabricator.kde.org/D22291