Please can you provide a diff patch so that I can understand which line has been replaced by what and provide a clean fix. Tex's change will only work where pbuffers work correctly which isn't the case on all platforms, it's not a real solution.
Edit.: I have looked at the previous comments, jimmypag's solution can't work with the latest JOGL version. Tex's suggestion is less dangerous but what happens if you call both offCaps.setFBO(true) and offCaps.setPBuffer(true)? If it works, it's acceptable in a patch.