[xmonad] How is this screenshot done?

Hy, I found this screenshot: http://haskell.org/haskellwiki/Image:Screen-ohmega-tab-gnome-twopane.jpg How is the tabbing done in this screen? The upper right window seems to have multiple tabs. Is this possible using xmonad? Thanks for any help -- Dominik Bruhn mailto: dominik@dbruhn.de