So, to summarize -
With gtk paths, mouse doesn't work but pressure/ tilt does.
Without GTK paths mouse does work but pressure/ tilt doesn't.
There must be a way to fix this as so many people have it working but
removing GTK does not work for me, especially as Gimp makes far more use of
pressure and that also fails with no GTK. As Gimp is also affected it must
be due to GTK so for now I am going to have to give up on this one but I
will post on the GTK forum to see what happens there.