FVWM or F? Virtual Window Manager is a Window Manager for X11
Fvwm is a window manager for X11. It is designed to minimize memory consumption, provide a 3D look to window frames, and a virtual desktop. Fvwm has also overcome the distinction between configuration commands and action commands. Configuration commands typically set fonts, colors, menu contents, and key and mouse function bindings, while action commands do things like raise and lower windows. Fvwm makes no such distinction and allows anything to be changed at any time.
FVWM was created by Robert Nation while working for the United States DOD in 1993, in 1994 he gave Charles Hines control of the project.