Windows Vista build 5212 (winmain)

Windows Vista build 5212 (with a build tag of 5212.winmain.050726-1915) is a pre-Beta 2 build of Windows Vista. It leaked on 2016-12-19 at BetaArchive. It 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 the same as 5112.

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