The Openbox is a highly configurable window manager with extensive standards support that, like many other *boxes, initially began its life as a Blackbox fork. It was eventually re-written entirely from scratch as of version 3.0 and it no longer bears any relation to Blackbox.
Openbox aims to be extremely standards compliant. It thoroughly supports the freedesktop.org window manager specification and strictly follows the ICCCM standard. This allows Openbox to be capable of supporting any application that follows these specifications, as well as allowing it to be run under both the GNOME and KDE desktop environments.