Creating the .invisible.txt file was done using non-assertion commands.
The tests have been failing for some and it seems like the commands
did not run correctly. Running them with assertions will make sure
that they will run (or fail correctly).
This reverts the last few commits which worked around a focus bug
in GTK. This bug is now (I hope) fixed, so I'm dropping the
workarounds so the tests will confirm whether it's fixed.