- Support for H264 (MP4) is now built in on Mac OS X Snow Leopard (10.6) and newer through native APIs.
- HTTP/2 (draft14) and ALPN have been implemented.
- Added ability to recover from a locked process in the "SeaMonkey is already running" dialog on Windows.
- Added ECDH support for WebCrypto.
- The console.table function has been added to the Error Console.
- CSS transitions start correctly now when started at the same time as changes to display, position, overflow, and similar properties.
- Fixed several stability issues.