Ion is a tiling (no overlapping windows) window manager that
also has PWM-style tabbed frames which can contain multiple client
windows. These features help to keep windows organized and to switch
quickly between them. Ion was designed primarily as an efficient and
unobtrusive window manager for users who prefer the keyboard.
This is the latest stable release of Ion (3). A pwm3 binary is built
too, which starts Ion with floating workspaces as the default, thus
replacing the PWM window manager.
Please note that the author of Ion stopped all development and support
for this tool - even its web page has been taken offline.
A community effort started a forked project called "notion", which can
be found at http://notion.sourceforge.net/