Windows 10 build 9780

Windows 10 build 9780 is a pre-Technical Preview build of Windows 10. This build was leaked on 26 January 2019. It is currently the earliest leaked build of Windows 10, and due to its earliness it is identified as Windows 8.1 in many areas and still has kernel version 6.3. Because it is in the fbl_partner_eeap branch, the timebomb is broken and the build can be booted on the current date. Despite it having a start menu, native support for Windows Store apps in windowed mode has not been introduced yet by default.

Aero changes
DWM-based window animations (particularly window open and close) have been changed to simpler transitions.

A new start menu
A new start menu has been introduced, merging a Windows 8 and Windows 7 styles.

Home page in File Explorer
There is a new page in File Explorer named Home, and it is displayed when you first open an aforementioned app.

Wallpapers
and  wallpapers have been swapped, resulting in Windows 8.1's   becoming a default wallpaper.

Metro live colorization
Usually, Metro picks a different color from the wallpaper than Aero.

Window thumbnail color error
Window thumbnails on the taskbar do not change color, but the user can change it after the computer restarts.