Source: Albacore via Twitter
Many Windows enthusiasts love the Aero blur effect. Blurring has been around in some form or another within Windows for a long time, and it has evolved over the years, but the Aero effect is still the standard for some. Software archeologists have uncovered what may be the first instance of the Aero effect running on a version of Windows. A Twitter user known as evil_pro_ tested the effect on actual hardware running Windows Longhorn build 4020 (via Albacore on Twitter). The code for the effect is in builds 4015 and 4017 but reportedly does not work the same as on build 4020.
Longhorn builds included several features during its initial development process, but the branch was reset in 2004 due to several issues. While Microsoft had to start over, some elements from Longhorn made their way into later versions of Windows, including the Aero effect in Windows Vista.
The Aero blur effect used the graphics of a PC to render parts of the Windows interface. Microsoft has since taken a different approach to blurring elements of its operating system. Windows 11 has a mica effect that uses fewer system resources because it only samples the desktop wallpaper once. This allows a PC to blur parts of the screen without having to continually sample whatever is behind an active window.
