Which GUI environment you choose to host your application is one of the most important background decisions you will make about it. The decision will have significant technical consequences, because although the features offered by different desktops are broadly similar they are by no means identical. The decision will also control which other applications you can most easily integrate yours with. Finally, the decision will have political consequences as well, because both of the major desktops have vociferous advocates, associated communities of interest, and major corporate backers.

To understand why choice of desktop is such a sensitive issue, a little review of the history of major Unix desktop environments is in order. Excluding one or two that have been obsolete for so long that they have no influence on present-day conditions, there have been four: NeXTstep, CDE, KDE, and GNOME.

NExTstep was the proprietary GUI environment associated with Next, whose premature attempt to build inexpensive color workstations we touched on in the History chapter. In 1993 NeXT went software-only to concentrate on developing and licensing NeXTstep, and successfully closed a licensing deal with Sun Microsystems. In 1997 Apple bought out Next in order to fold its software technology into the next-generation Macintosh operating system; that technology became a substantial part of Mac OS X. A screenshot of a NeXTstep desktop was included in the History chapter.

While NeXTstep itself was proprietary, attempts to build emulations of its look and feel have attracted persistent minority support in the post-1997 open source community. We have already touched on two of these, the AfterStep and WindowMaker window managers. There is a GNUStep project attempting to implement Apple's published standard interfaces for NeXTstep, but there is no realistic prospect that it will overtake GNOME or KDE in the struggle for developer mindshare. Nevertheless, NeXTstep continues to serve as a design model for the more widely used present-day desktops.

CDE, the Common Desktop Environment, was an attempt to do for desktops what the X window system had done for the underlying graphics engine. It was develped by a consortium of proprietary Unix vendors including IBM, Hewlett-Packard, and Sun Microsystems and built around the proprietary Motif toolkit. CDE successfully replaced a gaggle of single-vendor proprietary desktops in the early 1990s. But like Motif, CDE proved unable to keep up with open-source competitors after 1997 and has since been abandoned by its former patrons.

KDE, Kool Desktop Environment, began life in 1996 as an attempt to produce an open-source equivalent of CDE for Linux. Ther primary motivation of the developers was evangelistic, to build a GUI that would take Linux to end-users. Accordingly the aims of KDE almost immediately enlarged from just producing a desktop to shipping an entire application suite including a Web browser, word processor, spreadsheet, and other productivity tools.

While the KDE developers made rapid early strides towards their technical goals, they also made a serious political mistake. The Qt toolkit on which they based their desktop was under a license that did not completely conform to the developing norms of the open-source community. This led to a heated controversy, with opponents expressing concern that that Trolltech, the small Norwegian consulting company behind Qt, might eventually use its control of the code in damaging ways.

Trolltech eventually cbanged its license to be fully conformant with community norms. But by that time, the damage had been done. The GNOME project was founded in 1997 as an explicit rival of KDE. To the chagrin of the KDE hackers, it marketed itself more effectively than KDE had done and swiftly attracted a larger developer community. KDE's situation was not helped by the fact that its core group was located in Germany rather than the United States, and accordingly found it somewhat more difficult to recruit a large talent base.

Like KDE, GNOME quickly expanded its mission to supporting an entire application suite. The two projects settled into intense and sometimes bitter rivalry, occasionally punctuated by cooperation on technical standards such as drag-and-drop protocols. The arms race between them has probably stimulated greater code productivity by both teams, but has done so at the cost of dividing the developer community and the open-source applications space.

This situation is probably not stable, especially not given that in early 2004 a single corporate entity (Novell) acquired the two companies most responsible for funding KDE and GNOME development respectively. But it is at time of writing too early to tell whether the split will be resolved by the disintegration of one project or the merger of both.

We cannot tell you which environment is “best”, as the development of both moves so quickly that anything we were to say about relative capabilities would be likely to have changed by the time you read this. There will be, alas, no substitute for doing your own evaluation.