Notion is a tiling, tabbed window manager for the X window system:
* Tiling: you divide the screen into non-overlapping 'tiles'.
  Every window occupies one tile, and is maximized to it
* Tabbing: a tile may contain multiple windows - they will be 'tabbed'
* Static: most tiled window managers are 'dynamic',
  meaning they automatically resize and move around tiles as windows
  appear and disappear. Notion, by contrast, does not automatically
  change the tiling. You're in control.

Features include:

* Workspaces: each workspace has its own tiling.
* Multihead: the mod_xinerama plugin provides very nice dual-monitor
  support.
* RandR: mod_xrandr expands on mod_xinerama and picks up changes in
  the randr configuration without the need for restarting Notion
* Extensibility: Notion can be extended with lua scripts.