of the display manager but have input and output on the computer where the X server runs (which may be the computer in front of the user or a remote one). The X Window System ships with XDM as the basic supplied display manager. Other display managers include GDM (GNOME), KDM/SDDM (KDE), WDM (using the WINGs widget set used in Window Maker) and entrance (using the architecture used in Enlightenment v.17). User interface elements Early widget toolkits for X included Xaw (the Athena Widget Set, 1983), OLIT (OPEN LOOK Intrinsics Toolkit, 1988), XView (1988), Motif (1980s) and Tk. OLIT and XView function as the base toolkits for Sun's legacy OpenWindows desktop environment. Motif provides the base toolkit for the Common Desktop Environment (CDE), the desktop environment used on commercial Unix systems such as Solaris, AIX and HP-UX. (Solaris 10 includes both CDE and GNOME, with the latter the preferred desktop environment .) Toolkits developed more recently include Qt (1991- , used by KDE), GTK+ (1997- , used by GNOME), wxWidgets (1992- ), FLTK (1998- ), FOX (1997- ) and fpGUI (2005-current). Extensions Scheifler and Gettys designed the X server to be simple but extensible. As such, much functionality now resides in extensions to the protocol. At the protocol level, every extension can be assigned new request/event/error packet types. Extension features are accessed by client applications through extension libraries. Adding extensions to current X server implementations is reportedly difficult due to a lack of modularity in the server design. It is a long-term goal of the XCB project to automate generating both the client and server sides of extensions from XML protocol descriptions. The following table provides a partial catalog of extensions that have been developed, sorted roughly by recency of introduction: Obsolete extensions See also Xlib Intrinsics (Xt) X Window System core protocol X logical font description Notes References archive.org has the 1990 edition. Further reading Robert W. Scheifler and James Gettys: X Window System: Core and extension protocols, X version 11, releases 6 and 6.1, Digital Press 1996, Introduction to X Windows[sic] External links X.Org Foundation (official home page) X.Org Foundation wiki X Window System Internals Kenton Lee's pages on X Window and Motif X11 Extension tutorial protocols and architecture Application layer protocols Remote desktop protocols X Window extensions