GEM/4 was supplied as part of CCP's "Artline" program; it does not have a Desktop of its own.
The Artline "about" box. GEM/4 has built-in functions to produce colour gradients.
Artline supports checkboxes and radio buttons for its preferences, but it is not known whether these are drawn by Artline or by the underlying GEM/4.
GEM/4 is able to attach menus to windows as well as to the top of the screen; though only one menu is active at any one time.