Mozilla and Microsoft have butted heads before over hardware acceleration on Windows, with the former saying it uses the same APIs (application programming interfaces) on Windows 7 as Microsoft to speed up Firefox 4.
Microsoft's Gavin acknowledged that he was aware of Mozilla developers' comments about IE9, but declined to comment on them. Instead he said, "Our focus has been to hardware accelerate text, video, audio and graphics. That's our implementation of hardware acceleration."
Gavin also explained the decision to drop Windows XP from the list of supported operating systems for IE9, a move that flies in the face of statistics: Windows XP still accounts for 61% of all copies of Windows now in use.
"We knew we didn't want to optimize for the lowest common denominator, you need a modern operating system," Gavin said. "[Supporting XP would have been] optimizing for the lowest common denominator. It's ten years old. That's not what developers need to move the Web forward."
Gavin declined to spell out Microsoft's adoption goals for IE9.
Both Hachamovitch and Gavin also repeated themes Monday that Microsoft has deployed in the past to describe the new browser.
"The browser should be a stage," Hachamovitch said.
"We wanted to change the way consumers experience the Web," said Gavin. "How do you get the browser out of the way? The browser is the theater, but people pay money for the play, not the theater."
Those comments were echoes of Microsoft's previous assertion that IE9's new streamlined look -- which some have said resembles Google Chrome's minimalist user interface -- was a design choice to make the browser fade into the background, and put Web content at the forefront.
They also talked up the idea that IE9's new "pinning" feature makes Web sites more application-like. Users can "pin" a site to the Windows 7 taskbar, just as they can a native Windows application, such as Microsoft Word or Adobe Photoshop, to launch it with a single click.
Monday, Microsoft said more than 1,000 sites have taken advantage of pinning -- and another Windows 7 feature called "jump lists" -- to make their sites behave more like an application. Some of those sites are offering special deals to users for pinning, including Hulu, which will give customers a free month of the Hulu Plus service for adding the site to their taskbars.
"Pinning and jump lists make sites site more app-like," said Gavin. "Even with the explosion of apps in the last couple of years and all the apps on devices, the Web is the number one interactive mechanism. But the Web has trailed behind the app experience."
According to Gavin, more than 40 million copies of IE9's beta and release candidate, or "RC," had been downloaded by users prior to Monday, a number he said was a record for a Microsoft browser preview.
"We've been humbled by the adoption of IE9," Gavin said.
Microsoft posted IE9 to its download servers at 9 p.m. PT Monday. The download, which weighs in between 17MB and 35MB -- the 64-bit versions for Vista and Windows 7 are larger -- is available from the company's Internet Explorer site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@computerworld.com.