before the introduction of apple's x11.app, xdarwin was the only x11 server available for os x. according to the xonx project, x11.app itself contains code from xdarwin. programs such as openoffice.org use xdarwin to run in the x11 windowing environment, either in a rootless or full-screen mode. a version of the program was created for mac os x panther or higher that runs in the native aqua interface.