 A number of other desktop environments also exist, including (but not limited to) CDE, EDE, GEM, IRIX Interactive Desktop, Sun's Java Desktop System, Jesktop, Mezzo, Project Looking Glass, ROX Desktop, UDE, Xito, XFast.Moreover, there exists FVWM-Crystal, which consists of a powerful configuration for the FVWM window manager, a theme and further adds, altogether forming a "construction kit" for building up a desktop environment.X window managers that are meant to be usable stand-alone — without another desktop environment — also include elements reminiscent of those found in typical desktop environments, most prominently Enlightenment.