Testers unearthed a version of the Aero theme for Windows Vista released in early 2003.

If you’re interested in the history of Windows, you probably know a little about Longhorn, Microsoft’s internal codename for the OS update that would eventually become Windows Vista. Microsoft planned a huge list of new features for Longhorn (and its planned successor, codenamed Blackcomb), many of which never saw the light of day. Longhorn was supposed to include a file system to replace NTFS, which we still haven’t got nearly two decades later.

One of Vista’s most notable and memorable additions was the “Aero”design, which used Direct3D to draw translucent glass windows that could fade in and out of view smoothly, replacing the 2D windows from older versions of Windows. Over the weekend, Twitter user @thebookisclosed (who has a habit of digging through older development versions of Windows) introduced us to the earliest known version of Aero in a March 2003 Longhorn development build, almost four years before Vista. be released to the public.

This early Aero effect is very different from what we ended up with in Windows Vista – the translucency and smokey glass look here, but the final effect seen in Windows Vista and Windows 7 is shinier and the blurriness is more pronounced. (In the Longhorn version of the effect, blur reduction could create readability issues if, for example, text in the title bar and text in the underlying window were run together.)

While the Aero effect and proto-sidebar will be recognizable to Vista users, these builds of Longhorn from 2003 bear little resemblance to the OS that Microsoft will finally release and won’t get a very warm welcome in early 2007. to “reboot”Longhorn development in 2004 by discarding these early builds and starting fresh with the Windows Server 2003 codebase. the effort spent on XP SP2 further delayed the release of Longhorn.