Mozilla Firefox 7.0 Beta 4 发布

　　Firefox 7.0 发布了第四个 beta 测试版本，下载地址：Mozilla Firefox 7.0 Beta 4

　　改进记录：

• Drastically improved memory use
• Added a new rendering backend to speed up Canvas operations on Windows systems
• Bookmark and password changes now sync almost instantlywhen using Firefox Sync
• Added support for text-overflow: ellipsis
• Added support for the Web Timing specification
• Added an opt-in system for users to send performance data back to Mozilla to improve future versions of Firefox. This can be enabled by installing an add-on
• Fixed several stability issues