They fixed the "bug" I reported to them. There is finally ample room between the titlebar buttons and the tabs!
The hardware acceleration looks nice as well.
Before the betas came out, I dared Mozilla to get me to dump Chrome. They have succeeded in that challenge.
Firefox 4 beta 5 is now available and offers new hardware acceleration, multimedia and security features.
The latest beta, for example, offers hardware acceleration through Direct 2D by default. Direct 2D was introduced with Windows 7, was made available for Vista, and exploits built-in graphics hardware in Windows PCs with DirectX 10 to enhance performance on graphics heavy websites, said Firefox lead developer Mike Beltzner in his blog today.
“You should notice that some pages are a lot faster and more responsive, in  particular, pages that use advanced animated graphical effects,” added other Firefox developer Bas Schouten in his blog about the feature.
Beta 5 also includes a new Audio API for visualizing audio that exposes raw audio data within the video and audio elements of HTML5. Mozilla claims that developers can use this API to change how users experience the web.
“Until now, people haven’t had the ability to interact with sound on the Web in all the creative ways that video and images allow,” Beltzner wrote. “With this new API, developers can read and write raw audio data within the browser, presenting audio information in completely new ways that could allow, for example, for people to visually experience a speech or a song through Firefox.”
Beta 5 also supports the HTTP Strict Transport Security (HSTS) protocol for addiitonal security. “This allows web sites to “insist that they only be loaded over SSL,” Mozilla notes.
Beta 6 is very tentatively set for release on September 10 but that may slip by as much as a week, project leaders indicate. Firefox 4 entered beta testing in June.
