|Original author(s)||Tom LaStrange|
In computing, twm is Tom's Window Manager which was then renamed by X.org to Tab Window Manager when they adopted it as their defacto window manager. It is the standard window manager for the X Window System, from version X11R4 onwards. twm is a re-parenting window manager that provides title bars, shaped windows and icon management. It is highly configurable and extensible.
Using twm 
twm's interface is different from modern common X window managers and desktop environments all of which tend to work similarly to the Apple Macintosh or Microsoft Windows. New users often find twm difficult without reading the manual page.
In the default configuration of twm, the title bar has two buttons:
- Resize button (nested squares): the user clicks here, drags the mouse pointer to the edge to be moved, then releases when the window is the desired size.
- Iconify button (circle): reduces the window to an icon.
There is no title bar button to close a window. A left click on the desktop brings up a menu, which includes an option to delete (close) a window.
A left click on the title bar brings the window to the top of the window stack; a middle click moves the window; a right click sends the window to the bottom of the window stack.
When a new window is created, a 3×3 grid is displayed following the mouse pointer, waiting for the user to click where the window should appear — left-click to appear in that position with that size, middle-click to resize the window before its creation, right-click to appear at that position but long enough vertically to reach the bottom of the screen.
Note that any of the above may be changed with appropriate changes to the configuration file. (The system file is typically /etc/X11/twm/system.twmrc and the user file is typically ~/.twmrc .)
twm was written by Tom LaStrange, who was working at Evans and Sutherland, which was part of the X Consortium, for a replacement for the uwm: "I sat down at my monochrome Sun 3/50 and typed vi twm.c and then opened the X11 documentation. twm was my first X program. About six months later, I convinced my manager to let me send a copy to the comp.windows.x newsgroup for testing." A version for X11R1 was published on the Usenet newsgroup comp.unix.sources on June 13, 1988
Months later, Jim Fulton of the MIT X Consortium approached Evans and Sutherland and asked them to turn over the code maintenance to the X Consortium and Fulton then made it compliant with the then nascent Inter-Client Communication Conventions Manual. Subsequently, twm was released as the standard sample window manager for X11R4, replacing uwm.
According to Fulton, the word "tab" was picked because it conveniently started with 'T' and it put the emphasis on the squeezing feature window title bars, which made them look like folders with tabs.
twm was originally written by Tom LaStrange. Later contributors include Jim Fulton, Keith Packard and Dave Sternlicht, all of whom were employees of the X Consortium.
- Tab Window Manager (xwinman)
- An Overview of twm (Tom's Window Manager) (PDF) — Tom LaStrange, Xhibition '89 Conference Proceedings — concerning pre-ICCCM versions of twm
- From the Desktop: Tom LaStrange Speaks!: Talking with a Man Named Tom (Brian Proffitt, LinuxPlanet, Tuesday 6 February 2001)