As noted earlier, Apple's X11 distribution is based on the open source XFree86 Project's XFree86, Version 4.3. The X11 package has been optimized for Mac OS X and has the following features:
X11R6.6 window server
Support for the RandR (Resize and Rotate) extension
Strong integration with Mac OS X environment
A Quartz window manager that provides Aqua window decorations, ability to minimize windows to the Dock, and pasteboard integration
Can use other window managers
Compatible with Expose
Supports rootless and full-screen modes
Customizable Application menu, which allows you to add applications for easy launching and to map keyboard shortcuts
Customizable Dock menu, which allows you to add applications for easy launching, to map keyboard shortcuts, and to list all open windows
Finder integration, which supports auto-detection of X11 binaries and double-clicking to launch X11 binaries, starting the X server if it is not already running
Preference settings for system color map, key equivalents, system alerts, keyboard mapping, and multi-button mouse emulation
Hardware acceleration support for OpenGL (GLX) and Direct CG (AIPI)