Wine 1.7.21 adds the following features and functionality:
- Support for critical sections in the C runtime.
- Unicode data updated to Unicode 7.0.
- Support for interlaced PNG encoding.
- Initial stub for the Packager library.
- Various bug fixes.
More details on this routine Wine 1.7 development release leading up to Wine 1.8 can be found via the official release announcement posted to WineHQ.org.