Matchbox (window manager)

Matchbox is a free and open source window manager for the X Window System. It is mainly intended for embedded systems and differs from most other window managers in that it only shows one window at a time. It is used by Maemo on Nokia Internet Tablets, the Neo 1973 smartphone based on Openmoko, the Vernier LabQuest handheld data acquisition device for science education, as well as on the XO-1 of the One Laptop Per Child Project. It has been replaced on later OLPC software builds by Metacity.
Matchbox 2.
Matchbox Window Manager II is a complete rewrite of the original m-w-m. It is in early stages of development.