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Computerworld - Adobe on Thursday backpedalled from a claim that its popular Flash Player did not work with OS X Lion's hardware acceleration, saying that a testing mistake led it to the wrong conclusion.

Earlier this week, Adobe said that Flash Player -- the most widely-used browser plug-in on the planet -- consumed a large percentage of a Mac's processor cycles when playing YouTube videos, an issue that could lead to a general slow-down of the machine.

Adobe initially said the Flash Player problem on Mac OS X 10.7, aka Lion, was "possibly related to disabled hardware acceleration" in the operating system.

Flash Player 10 accelerates video playback by tapping the Mac's graphics processor unit (GPU). The plug-in supported hardware acceleration on Snow Leopard, Lion's predecessor.

On Thursday, Adobe recanted.

"The final release of Mac OS X Lion (10.7) provides the same support for Flash hardware video acceleration as Mac OS X Snow Leopard (10.6)," said Rob Christensen, an Adobe product manager, in a post to a company blog. "The previous 'Known Issue' described in a tech note suggesting that video hardware acceleration was disabled in Lion was incorrect and based on tests with a pre-release version of Mac OS X Lion that related to only one particular Mac GPU configuration."

Although Apple shipped Lion Tuesday, starting last February it had delivered several developer preview builds of the operating system.

The retraction by Adobe was only the latest skirmish in a long war between Apple and Adobe over Flash.

The two have been at loggerheads since Apple refused to allow Flash on its iPhone in 2007, but the dispute grew heated last year as the companies traded blows over Flash content on Apple's iOS mobile operating system, with Apple CEO Steve Jobs trashing Flash in an April missive and the co-chairs of Adobe's board of directors accusing Apple of undermining the Web in mid-May.

Last October, Apple dropped Flash from Mac OS X. Previously it had bundled the plug-in with the operating system, and maintained it by issuing its own security updates for the Adobe program.

At the time, Apple argued that yanking Flash from OS X was a security move. "The best way for users to always have the most up-to-date and secure version is to download it directly from Adobe," a company spokesman said nine months ago.

Lion does not include Flash Player.

Adobe has also published a long list of programs that have issues running on Lion or in Safari 5.1, ranging from Flash Player and Photoshop to Reader and LiveCycle.

Apple shipped Safari 5.1 with Lion, and updated the browser to the same version number for Snow Leopard, on Tuesday.( For example, Adobe Reader, a standalone PDF viewer that also provides browser plug-ins, doesn't work properly with Safari 5.1 in some corporate situations.

Like many third-party developers, Adobe must also recode much of its software to take advantage of new features in Lion, like the operating system's automatic application resume and full-screen mode. Adobe acknowledged the work it needs to do, but didn't promise to support all of Lion's new features and gave no timeline for updates to its software.

"Adobe will investigate which [Lion features] make sense to our customers for inclusion in future versions of our products," the company said.

Adobe also reminded customers that Create Suite 2 (CS2), a 2005 suite that included Photoshop, Illustrator and other programs, does not work in Lion because Apple dropped support for software compiled for the PowerPC processor.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at  @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@computerworld.com.

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