From the Read Me:
This update addresses several issues in the X11 for Mac OS X package, enabling it to better handle:
- GLX stereo visuals
- offscreen rendering to GLX Pbuffers and Pixmaps
To tell X11 to take advantage of stereo visuals, enter:
$ defaults write com.apple.x11 enable_stereo -bool true
This update also addresses font issues present in X11 1.1.2, and is recommended for all users.
FYI - Stereo viewing is a common technique to increase visual realism or enhance user interaction with 3D scenes and is typically used in scientific applications.