Openbox is a free, stacking window manager for the X Window System, licensed under the GNU General Public License. Originally derived from Blackbox 0.65.0 (a C++ project), Openbox has now been totally rewritten in the C programming language and since version 3.0 is no longer based upon any code from Blackbox.Openbox is designed to be small, fast, and fully compliant with the Inter-Client Communication Conventions Manual (ICCCM) and Extended Window Manager Hints (EWMH).