freedesktop.org (xdg) is open source and discussion project working on interoperability and shared technology for X Window System desktops. The most famous X desktops are GNOME and KDE, but developers working on any Linux/UNIX GUI technology are welcome to participate. They create open standards that project can comply with.

FreeSoftwareFoundation

freedesktop.org homepage
NETWM - freedesktop.org spec
Development of a xdg compliant menu for Puppy thread