Hi Tom,
I think the eventual GUI will be quite complex, but I am trying to keep things as simple as possible....and starting right from the basics.

The system I am developing is a type of simulation / learning environment - I will begin to draw out some designs in the next week.
I would appreciate it very much if you could provide the source for your project GUI. I too will be developing with LWJGL.
Regards,
Antony Ribot
Creating your own gui system in opengl can be alot of work. It depends on wich components you need. Creating a button in opengl is very simple. Lists, TextAreas, ComboBoxes, Containers and Frames are of course much more difficult. How complex will your gui be?
Btw. I did my own gui system for
Squareheads. All done in lwjgl. You can have the source if your interested.