Windows Longhorn WinHEC 2004 Aero demo build

The Windows Longhorn WinHEC 2004 Aero demo build (build number unknown; commonly, but wrongly quoted as 4069) is a Milestone 7 build of Windows Longhorn. It was shown during WinHEC 2004 when Jim Allchin used it to demonstrate Aero transparency in Longhorn. In that demo, this build was shown with the "Tree" wallpaper found in build 4083 and later.

Three high resolution screenshots of this build from the WinHEC 2004 Longhorn Driver Model presentation were shared by ReflectiaX on 30 April 2021.

Build number
The build number of this build is unknown. It is popularly known as "build 4069" as a result of a report from WinHEC 2004 stating that builds 4067 and 4069 were scheduled to be demoed, but this build number is almost certainly incorrect:
 * Tiles on the sidebar clearly show triangles in their upper right corner. These were first seen in build 4042.Lab06_n and can still can be found in Windows Server 2008 build 4066, but were removed in build 4067 (idx01).
 * The build tag is only visible in a low quality video released during WinHEC by Tom Warren, where it's illegible. Nevertheless, the length of the build tag is discernible, and it's consistent with it being of the form "For testing purposes only. Build 40xx.private/lab06_demo.yymmdd-hhmm", same as build 4050, demoed at PDC 2003. Given that code from build 4050 had been reverse-integrated into main by the time of Server build 4066 (in which said code is heavily bitrotted and broken), it seems unlikely that the lab06_demo branch remained operational until build 4069 with Aero UI preserved virtually unchanged from build 4050.

Based on this, the actual build number is believed to fall somewhere between 4050 and 4066. It is possible that this build is the same that was demoed at PDC 2003.