# What’s new in CotEditor 3.0 on Mac

Swift migration
  All of the source codes for CotEditor was completely rewritten in Swift from Objective-C.
Tabbed window
  Finally, CotEditor now supports tabbing windows on Sierra. On CotEditor 3.0, the tab behavior was improved from the standard Sierra implementation in order to let it behave more naturally.
Brushed-up look
  Graphic images like toolbar icons and application icon were also updated to get a more modern look.
New text search engine
  The find panel’s regular expression engine was changed from Onigmo (Oniguruma-mod) to the ICU library. Thanks to that, the line-up of text search is updated with new useful items and not only for the regex search but also for the normal texture search.
Support macOS Sierra
  Hello to Sierra and good-bye to Mountain Lion and Mavericks. So, CotEditor now supports from OS X 10.10 to macOS 10.12.

## See also

- Release notes
- What’s new in CotEditor 2.5?
- What’s new in CotEditor 3.1?