I've got a small bathroom with an awkward layout. I'd like to replace the normal door with a bi-folding door to make access easier, however a standard bolt or lock will just pull out if you pull/push the door in the middle. Does anyone know what sort of lock will work here? I don't want to fit a simple hook+eye as (apart from being ugly) the door should be openable from the outside in an emergency. Any ideas or recommended products?