Windows 10 build 9780

Windows 10 build 9780 is a pre-Technical Preview and the earliest available build of Windows 10, which was uploaded to BetaArchive on 26 January 2019. This build was originally released to Microsoft partners participating in the Ecosystem Engagement Access Program (EEAP), as indicated by the  branch.

Due to its earliness, this build is identified as Windows 8.1 in many areas and still has kernel version 6.3.

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

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

Home page in File Explorer
File Explorer received a new page called Home, it opens when you launch the app.

Windowed Metro applications
This build introduces native support for Metro apps in windowed mode, which is disabled by default. It can be enabled by merging following registry setting:

However, title bars will use the same style as Win32 applications. Also, the feature itself has bugs.

Search
Also, this build includes Search from build 9821, which is disabled by default. It can be enabled by merging following registry setting:

The feature itself has bugs

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

Timebomb
Like other Windows 10 builds found in the  branch, this build contains a non-functional timebomb and as a result can be installed on the current date.

Window thumbnail border color
If window auto-colorization is enabled, the window thumbnail borders on the taskbar do not change color even after the wallpaper changes. This issue can be remedied by manually changing the window color through the Control Panel.

Safe Mode
Trying to boot into Safe Mode (whether via System configuration tool or Recovery Options) results in a black screen.

VMware Workstation
Attempting to install this build through VMware Workstation by using the Easy Install mechanism will lock the newly created user account out with a password expiration warning. It can be remedied by adding a password to the user during the VM creation process.