The major development changes in the latest version include:
- Support for the HTML 5 <video> element.
- Initial support for web worker threads.
- You can now drag and drop tabs between browser windows.
- Ability to make use of Aero "Glass" in XUL.
- Support for CSS 2.1 properties: ::before and ::after, and white-space:pre-line.
- Support for CSS 3 properties: -moz-border-image, word-wrap: break-word, text-shadow, box-shadow and column-rule.
- Performance improvements and new preference values for color management profile support.
This version is not a fully released version and only a milestone build for the latest browser in the making, you should install it only if you know about development and testing.