GDE is an X-window sequence analysis package that is designed to give a graphical interface to command line UNIX software. It was originally written by Steve Smith while he was at Harvard. Steve was later hired by GCG to wrap his interface around their product, and the result is the SeqLab interface (especially the editor).
We do have GDE running as a separate product, but the best way to take advantage of the GDE interface is to use GCG's SeqLab program.
Additional sources of info about GDE