I have found an easy solution to securing the joy stick of the GT-11 inside the aquapac.It's exactly the same as what Tom Chalko recommends but instead of a nylon washer i just used one of my son's foam bullets/darts he shoots out of his toy gun.Simply cut into sections and it fits the joy stick perfectly.
www.seabreeze.com.au/gallery/gallery.asp?imageid=5437
Good one choco, I've got to do something like that. My foam rubber block stops the thumb stick accidentally pressing in, but doesn't make it any better to operate.