Are GNOME and KDE window managers?
No, they are not. GNOME and KDE work with a number of different window managers, and encompass much more than the simple manipulation of windows. However, each one of them recommends a window manager that “works best.” For GNOME, the recommended window manager is Enlightenment, and for KDE it is the included KWM. Other window managers, such as Window Maker, integrate well with both GNOME and KDE.