Windows Longhorn build 4089

Windows Longhorn build 4089 is a private Milestone 7 build of Windows Longhorn. Two screenshots of this build have been leaked, one of which shows a prototype version of Windows Movie Maker based on Windows Presentation Foundation, the other shows a version of the Display Properties applet based on the aforementioned framework. The second screenshot was leaked on the BetaArchive Discord server by ReflectiaX on 26 January 2020.

In the BetaArchive topic "New Longhorn builds for a new decade" by Grabberslasher on 23 January 2020 where 33 Longhorn pre- and post-reset builds were leaked, including all then-unleaked builds showcased on UX.Unleaked, ReflectiaX mentioned that they once had a copy of this build, or at least another 4089 numbered build, but had since lost it.