by , 12:00 PM EST, March 15th, 2006

This year's South by Southwest (SxSW) Interactive festival, which concluded Tuesday on the eve of the famed music festival, served up a number of interesting panel discussions, but none of greater interest to Mac users than Tuesday's "Behind the Scenes: Developing OS X and Longhorn," which saw two former user interface designers at Apple and Microsoft�now co-workers at Frog Design�come together to discuss the design considerations that have gone into Mac OS X and Windows XP/Vista.

Cordell Ratzlaff, a nine-year Apple veteran, was head of Apple's human interface group during the time Apple acquired NeXT and began developing Mac OS X. Mark Ligameri spent six years at Microsoft working as a designer on Windows XP and Vista, as well Office 12 and other Microsoft projects.

Mr. Ratzlaff recalled for the audience the moment he was called into Steve Jobs' office at Apple, following Apple's acquisition of NeXT in 1997 but prior to Mr. Jobs assuming any official role at Apple whatsoever. With a pair of his best designers by his side, Mr. Ratzlaff stood in Mr. Jobs' office as the Apple co-founder called them "a bunch of amateurs" and launched into a long criticism of the Mac OS 8 interface.

Sensing that his job was in fact not on the line as he had thought�Mr. Jobs would, after all, have cut to the chase and fired him immediately�Mr. Ratzlaff was relieved to learn that what Mr. Jobs wanted from him was a new design for the Mac OS.

As it so happened, Mr. Ratzlaff and his team had already been working on a ground-up redesign of the operating system after they discovered that their original goal of porting the look-and-feel of Mac OS 8 completely to Mac OS X would be impossible. "We were only going to be able to get about 95% of the way there [putting the Mac OS 8 interface on Mac OS X], which is possibly the worst thing you could do," Mr. Ratzlaff said. The redesign had been scrubbed by higher-ups at Apple but was put back on track by Mr. Jobs.

With that, Mr. Ratzlaff and his team's list of requirements for the operating system, which had been called overly ambitious and led to laughter from engineers who heard of them only weeks prior, became mandatory. These included 32-bit color with alpha channels and QuickTime integration, all being able to run on a system with just a G3 processor and as a little as 8MB of video memory. Mocking up the operating system's design and functionality with Macromedia's Director, Mr. Ratzlaff frequently would remind Apple engineers that "Macromedia can do it, so why can't you?"

Mac OS X was first demonstrated to the public at Macworld Expo San Francisco in January 2000 after being shrouded in secrecy for nearly three years. Mr. Ratzlaff would depart from Apple following its completion but prior to its release, interested in pursuing other design goals. "[Mac OS X] 10.1 was not going to be nearly exciting," Mr. Ratzlaff said, exlaining how Mac OS X was the fourth major user interface design he had worked on at Apple, and by far the most ambitious.

Mr. Ligameri's experience at Microsoft was decidedly different, beginning with the contrasting management styles of the two companies. No Microsoft executive plays such an active role in the development of design like Mr. Jobs does at Apple; executives prefer to delegate design to the experts and stay out of it. Whereas Apple developed Mac OS X in complete secrecy and released it without any user testing whatsoever (a point Mr. Ratzlaff acknowledged surely led to some of the more glaring shortcomings that were corrected with Mac OS X 10.1), Microsoft has a penchant for demonstrating software long before its release, a poor and often frustrating decision in Mr. Ligameri's opinion.

Such a policy leads to ideas that and concepts that customers see and except soon afterwards but don't actually get to experience in a finished product sometimes for a number of years. Case in point: many of the design improvements Microsoft is delivering in Windows Vista this year were originally slated to be wrapped into a Windows upgrade set for release just 12-18 months following Windows XP. A number of security issues related to Windows XP that Microsoft had to focus engineering efforts on patching led to more than a two-year delay for that upgrade, however. The end result: what customers saw in 2003 and were told was going to be ready soon has yet to ship.

For a panel discussion on interface design development concerning Mac OS X and Windows the conversation was surprisingly civil and tame when it came to the subject of one company lifting ideas from the other. Mr. Ligameri explained that contrary to what many people believe, the Windows design team doesn't copy many Apple ideas. Most of those ideas are simply good ideas, and designers often conceive of goods ideas at similar times (a point Mr. Ratzlaff acknowledged).

"How much is just industry momentum moving in a certain direction versus how much is pixel for pixel reproduction?" Mr. Ligameri asked. Perhaps the most telling design element of Mac OS X, in his opinion, is simple attention to detail, so is Microsoft copying Apple when it decides to pay more attention to detail?

Mr. Ligameri also related the frustration that competing design teams experience all the time. For example, Microsoft had been developing a windows management system that was extremely similar to Apple's Expose when Apple first demonstrated the feature in Mac OS X 10.3 Panther to the public. Coupled with the fact that Apple was going to be shipping Mac OS X 10.3 Panther first, Microsoft designers were once again caught in the difficult position of having had pursued what was a wholly in-house development idea at the time but what the public will surely correlate with copying Apple's design.

Looking to the future, both Mr. Ratzlaff and Mr. Ligameri agree that operating system user interface design is moving away from a windowing system as content consumption replaces content creation as the primary use for a computer. Witness, for example, Windows Media Center Edition or Apple's Front Row software, which do away with dialog boxes, menus, and buttons. Your cell phone's interface, or even any of Apple's iLife applications, are similar examples.