an X11(aka X) window manager originally designed to provide integration support for the GNUstep Desktop Environment.

In every way possible, it reproduces the elegant look and feel of the NEXTSTEP(tm) user interface. It is fast, feature rich, easy to configure, and easy to use. It is also free software and part of the GNU Project, with contributions being made by programmers from around the world.

Window Maker includes compatibility options which allow it to work with other popular desktop environments, namely GNOME and KDE.

Source: the Window Maker WWW site,