Tab Window Manager.
A window manager for the X Window System. Twm provides titlebars, shaped windows, several forms of icon management, user-defined macro functions, click-to-type and pointer-driven keyboard focus, and user-specified key and pointer button bindings. It can be extensively configured by a startup file.
Twm was written by Tom LaStrange, Solbourne Computer; Jim Fulton, MIT X Consortium; Steve Pitschke, Stardent Computer; Keith Packard, MIT X Consortium; Dave Sternlicht, MIT X Consortium; Dave Payne, Apple Computer.
An extended version, vtwm, provides a virtual desktop.