To deal with the issue that the Mac OS X's X11 doesn't work with stereo very well, we have decided to release an Aqua version of chimera concurrent with production releases of the X11 version. The Aqua version will be labeled as a snapshot because we still recommend using the X11 version (the user interface works much better than the Aqua version). But if you need stereo, multisampling (full window antialiasing), or background transparency/opacity, then you need to use the Aqua version. Greg Couch UCSF Computer Graphics Lab