Fix sending keyboard input to various applications
Improve xtest and make more use of it, needed in particular for firefox.
I noticed that sending "?" doesn't work, which is due to KKeyServer::keyQtToModX
not returning the right modifiers.
That appears to affect the old path as well though.
Downstream report: https://bugzilla.opensuse.org/show_bug.cgi?id=1173968
Edited by Fabian Vogt