Tab Window Manager
The Tab Window Manager. It looks ugly by default. After a lot of work, it looks like this: still ugly, although no quite so bad. The icon manager (a taskbar equivalent) is in the upper left corner. Note that the windows can be shaped.
Supplied with XFree86.
TWM is supplied with XFree86. This version came with XFree86-4.3.0. This is the most recent version of XFree86 as of September 2003.
The man page is extensive and detailed. Understanding it requires some experimentation, but all the details are there.
The user can change the titlebar colours and fonts, the frame border colour and width, the buttons provided on the titlebar, and there's one alternative shape for the titlebar (tab instead of full length). Menu colours and fonts can be changed. The icon manager colours and fonts can be changed. Keys can be completely remapped. Until I started to write this, I never thought of TWM as themeable because it has such a distinctive look no matter what you do. But it does offer a lot of flexibility.
I don't use TWM often, but it's reliable. I don't recommend that anyone use it unless they're in an extremely retro mood. Even then, they may want to consider ctwm. ctwm is under active development and provides workspaces and greater flexibility in behaviour.
To me, TWM is characterized by the funky menus, the ugly titlebars, and its unusual method of resizing windows. To resize a window, you click on the resize button on the titlebar, then drag the mouse pointer to the side of the window you want to move. The side of the window sticks to the pointer and you can move it around until you release the mouse button. It's very strange.
Iconified windows can be stored either as icons on the desktop or in the Icon Manager, an option I've always preferred. See the image above - it's more or less the equivalent of a modern taskbar, but not as well controlled.
The current version seems to have a major problem with Xinerama. I can consistently lock it up in two screen mode, either horizontally or vertically arranged. Fortunately, Ctrl-Alt-Backspace will get you out quickly.
Usually available on a Linux system. Pretty much guaranteed to work. Very light on resources. Remap any key to do anything.
Ugly. No workspaces. Sliding focus only. Defaults could be more useful.