this utility actually uses native "desktop objects," as discussed above. Because of this, it does not offer the ability to move programs between desktops, or in fact to stop using virtual desktops at all, short of logging off, and Windows Aero only works on the primary desktop object. Microsoft had previously provided a Virtual Desktop PowerToy for Windows XP, which simulates many desktops with the more common method of hiding and showing windows in groups, each group being a different desktop. However, the functionality provided is less comprehensive than that of many other virtual desktop solutions (e. g. maintain a window in a given desktop even when its application bar button flashes, etc.). As with all virtual desktop utilities that work by hiding and showing windows, application compatibility problems are common, because application developers do not expect virtual desktops to be in use on the Windows platform. Historically, software packaged with some video card drivers provided virtual desktop functionality, such as in Nvidia's nView product (this product has been discontinued for GeForce card owners since Vista). Some of these programs provide eye-candy features similar to those available on Compiz. Many desktop shell replacements for Windows, including LiteStep, Emerge Desktop and others, also support virtual desktops via optional modules. Mac OS X Despite its Unix underpinnings, Mac OS X does not use the X Window System for its GUI, and early versions had no provision for virtual desktops. Beginning with Mac OS X 10.5 Leopard in late 2007, Mac OS X has shipped with native virtual desktop support, called Spaces, which allows up to 16 virtual desktops. It allows the user to associate applications with a particular "Space". As of Mac OS X 10.7 Lion, this functionality has been moved into Mission Control. Scrolling desktops were made available to Macintosh users by a 3rd party extension called Stepping Out created by Wes Boyd (the future founder of Berkeley Systems) in 1986. The code for this extension was integrated by Apple into a later version of the Mac OS, although the ability to create virtual desktops larger than the screen was removed. The code was used instead as an assist for visually impaired users to zoom into portions of the desktop and view them as larger, more easily discerned images. BeOS BeOS included an implementation of virtual desktops called "Workspaces". Up to 32 different Workspaces were supported. References External links Ars Technica: