Windows Vista build 5212 (winmain)

Windows Vista build 5212 (winmain) is a pre-Beta 2 build of Windows Vista. This build was leaked on 2016-12-19 at BetaArchive. This build includes Flip 3D, and notably, it reintroduced the sidebar, but it now runs in its own process rather than explorer.exe (which caused memory leaks in the former Longhorn project). Aero can be enabled on this build in VMware, unlike 5112, but it looks identical to the aforementioned build.

This is the leaked winmain compile, and it's not to be confused with the vbl_ux_dev_checkin compile.

Setup
Although setup is similar to aforementioned builds of Vista, the autorun prompt upon booting into setup now fits more perfectly on the screen and is positioned correctly.