The iPhoto Library and Aperture Library items can now be added to the Special menu, so that you can quickly browse your albums and projects, preview and copy photos, and view the associated metadata. To browse your iPhoto or Aperture library, you must have iPhoto 2 or later and Aperture 1.5 or later, respectively.
Previews offer several new features. With previews you can now:
display a slideshow of all the pages in a PDF file and easily view the associated metadata (title, author, page count and size, encryption, ... );
display a slideshow of all the images contained in a folder or smart folder;
copy pictures to the Clipboard and add them to iPhoto;
view a list of the files enclosed in a zip archive, display its uncompressed size and compression factor and save detailed zip archive information to a text file;
quickly view when documents were last opened and, in case they were downloaded or received as attachments, view where they were obtained from (URL, sender’s email address, message subject, ... ).
Making an application active by choosing a specific window from the Switch menu now causes only the selected window (and not all the application’s open windows) to be brought to the front.
Full Dashboard client names (e.g. Calculator DashboardClient) appear now in the Background-only Applications submenu of the Quit menu, so that running Dashboard clients can now be identified.
The display of IPTC (International Press Telecommunications Council) data associated with pictures has been revised and extended.
A bug that caused previews to incorrectly display music or movie durations longer than 1 hour has been fixed.
A bug that caused some third-party preference panes (TextExpander, Keyclick) not to appear in the System Preferences submenu of the Open menu has been fixed.
Some other minor bugs have been fixed.
Minimum required system version is now macOS 10.3.