An update to UCSF Chimera (version 1.11) is available for download.

General Changes:

• model-display checkboxes can be shown below the command line, and the model-active checkboxes can be hidden (see Preferences, Command Line)
• new input format: IMAGIC density map
• mouse focus (so that Chimera accepts typed input) can be restored by clicking into the Side View as well as the main window
• command-line “atomspec” expanded to handle surface piece names (such as from Multiscale Models)
• new flat ribbon publication preset
• “wall-eye stereo pair” option added to Save Image dialog
• revamped Getting Started tutorials, new Ribbon Styles image tutorial
• molecule descriptions (shown in the status line on mouseover) now read from mmCIF, not just PDB
• PubChem fetch changed to get structures from PubChem3D (NCBI) instead of Pub3D (Indiana University)
• command history navigation skips completely identical lines, and additionally pressing Shift (along with Ctrl-p, Ctrl-n, ↑, or ↓) goes to the previous/next occurrence of the same command (same initial string) instead of the * immediately adjacent command
• atom specification tolerates spaces after commas
• implemented standard keyboard shortcuts Ctrl-o,s,S,q (on Mac, Command instead of Ctrl) for File menu entries Open, Save Session, Save Session As, and Quit, respectively

Full release note are here

This is the last release for 32-bit operating systems, both the 32-bit and 64-bit versions run on Mac OS X 10.8 or later (including OS X 10.11 "El Capitan")

Chimera is developed by the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by NIGMS P41-GM103311).