Windows Longhorn build 4017

Windows Longhorn build 4017 is a Milestone 5 build of Windows Longhorn. On 2020-01-23, this build was listed on a thread by Grabberslasher, founder of the UX.Unleaked blog, to be released to the BetaArchive FTP, and was released as the first two builds of his 33 Longhorn/Vista builds on 2020-01-24, alongside build 4029 (Lab06 n). This build shares a lot of similarities with build 4015 (main), including a working Desktop Composition Engine that isn't different to the aforementioned build.