Do users want more or less choice when it comes to the look and feel of their operating systems? At the same moment Microsoft is betting customisation will be the order of the day, Apple Computer seems to be backing away from its user-controlled interface plans. A technology called Web Forms -- a Windows management feature in Microsoft's forthcoming .Net Framework and Visual Studio .Net tool suite -- lets developers simulate the custom "skins" that are already part of Microsoft Media Player 7, an integrated part of Windows Millennium Edition. Meanwhile, Apple -- which pioneered the customisable graphical user interface in the mid-1990s with its aborted Copland OS -- seems to be cooling to the notion of encouraging developers to create custom appearances for the Mac OS. With the debut of Mac OS 8's Appearance Manager in 1997, Apple offered the ability to provide custom GUI "themes" for a shipping version of its OS. Although the company never officially released the specifications, many third parties developed themes for Mac OS 8 and 9. Shareware developers Greg Landweber and Arlo Rose (a former Apple GUI engineer) also created Kaleidoscope, an appearance-customisation utility that lets users control all aspects of their interface, from desktop icons to scrollbars. All that may be changing with Mac OS X, which Apple said will debut as a public beta this summer and ship commercially at the beginning of 2001. Apple's next-generation OS is not expected to provide easy access to end-user customization in its sleek new GUI, Aqua. At the Microsoft Professional Developer Conference in Orlando, Fla., this week, Microsoft is presenting to its all-important developer constituency some details of the next-generation releases of its tools, operating systems and applications. And a key element of Microsoft's so-called .Net platform is its .Net "user experience". At Microsoft's initial unveiling in late June of its .Net strategy, company officials said to expect Windows .Net "user experience 1.0", aka the Whistler client interface, to provide a platform upon which developers and customers can rely during the transition to Microsoft's emerging "software-as-a-service" paradigm. Whistler is the successor to Windows 2000, which Microsoft officials said on Tuesday will ship some time in the second half of 2001. According to recent pre-alpha builds of Whistler Personal and Professional desktop releases examined by ZDNet News, Microsoft's Windows development team has spent time tweaking the kernel but, so far, little time updating the user interface. That doesn't mean Microsoft isn't planning some major user interface changes. The company has said it plans to add new speech, annotation and other natural-language capabilities to its Windows user interface in the not-too-distant future. But it's the possibility of skinning that really has some Windows developers enthused. "If implemented in the final release, the [customisable Windows manager] could allow a user to change the way Windows looks by using skins, the same way an application like Winamp does," noted Nate Mook, Webmaster of the BetaNews Web site. "For example, someone could create an 'Aqua' theme and have their Windows desktop looking identical to a fellow Mac OS X user's." There are other potential ways skins could be used in a Windows environment, as well, Mook said. "Different users on a [single] machine can create their own look to the system, as well," he said. "And corporations could make customised versions branding their corporate look on the desktop. Even OEM distributors could possibly brand Windows with new computers." Matthew Rothenberg and Adam Gillitt contributed to this report. What do you think? Tell the Mailroom. And read what others have said.