XDarwin

XDarwin was a display server supporting the X Window System (X11) ported to run on the Mac OS X and Darwin operating systems. It permitted the use of programs written for X11 on those operating systems. XDarwin was ported by the XonX project, an offshoot project created by XFree86 developers. It is integrated in the upstream source code of the XFr
Found on http://en.wikipedia.org/wiki/XDarwin
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