Windows 10 build 10240 (winmain prs)

Windows 10 build 10240 (winmain prs) is an unleaked build of Windows 10. Screenshots of the "About Windows" dialog and Windows Preinstallation Environment have been shown. Unlike build 10176, it has a timebomb, and reuses the Windows branding from builds 9821 to 10166 instead of the Windows 10 one.