Notion is a tiling, tabbed window manager for the X window system:

 o Tiling: you divide the screen into 'tiles'. Every window occupies
   one tile, and is maximized to it.
 o Tabbing: a tile may contain multiple windows - they will be
   'tabbed'
 o Static: most tiled window managers are 'dynamic'. Notion, by
   contrast, does not lay out or resize the tiles for you. You're in
   control.
 o Multihead: the mod_xinerama plugin provides very nice dual-monitor
   support
 o Xrandr: mod_xrandr picks up changes in the xrandr configuration
   without the need for restarting Notion