VirtuaWin

Windows had nothing of its own, so Johan Piculell wrote one. VirtuaWin does not go through the kernel's desktop objects the way Sysinternals Desktops does; it does the simple thing. When you switch desktops, every window belonging to the old one is hidden and every window belonging to the new one is shown. That means windows can move freely between desktops, a window can be made sticky and follow you everywhere, and single-instance programs never notice a thing.

The rest is what you would expect from a Unix pager ported to Windows: keyboard shortcuts, edge switching with the mouse, per-window-class rules, and a module mechanism for pagers and window lists. Steven Phillips took over maintenance in the mid-2000s, and the program runs essentially unchanged from Windows 9x to current releases. Microsoft's built-in desktops in Windows 10 work the same way, which makes VirtuaWin redundant for most people and still better for anyone who wants more than one hotkey.