Windows Longhorn build 4038

Windows Longhorn build 4038 is a Milestone 6 build of Windows Longhorn. On 23 January 2020, this build was listed on a thread by UX.Unleaked blog founder Grabberslasher to be released to the BetaArchive FTP. It was uploaded on 30 January 2020 in the seventh set of his 33 Longhorn/Vista builds, along with its server counterpart.

Setup
Although setup is mostly similar to previous builds of Longhorn, the cancel and back buttons have been removed, now making the top-left back and top-right exit buttons the only choices. Upon hovering over buttons, the icon of your mouse now changes as well. The upgrade page has also been updated, now having the buttons organized vertically, rather than horizontally.

However, this is the first build of Longhorn to contain the complete setup inside the  image, and setup will boot off the setup located inside the image.

New features and changes

 * The 3D views have been improved in usability when compared to 4033.main. The spinning icons have returned and the 3D views are interactable. However, it is still not possible to use Panorama to open files or folders.
 * It is now possible to move an Explorer window by clicking and dragging on free space within the upper navigation pane. In addition, double-clicking empty space on that pane also minimizes the window.
 * Replaced Help and Support by Assistance. However, it is almost nonfunctional since the links in its home screen only take to blank pages.
 * The settings page of Windows Explorer has been updated with bigger XP-style buttons for OK, Cancel and Apply.

DCE
The Desktop Compositing Engine now enables Direct3D shaders on capable hardware. Since DCE now has working Direct3D shaders, the new borders are now shown, which weren't found in earlier builds containing a working DCE. Although by default the borders will be opaque, you can get transparent borders by fooling  into believing that you have access to the private, unleaked Aero theme. You may enable DCE with the  command, although it requires a compatible graphics driver. Running  will also start the DCE.

Bugs

 * The preview pane may not show the common task options.

Installation

 * On some computers and virtualizers, this build can't be installed from CD boot as is. You must use the WinPE from a different build, or upgrade from a previous build.
 * On some computers, the hardware portion of setup will crash just after the second reboot and you will be instantly taken to the desktop.

Desktop Compositing Engine
While this build's Desktop Compositing Engine can render the DWM window frames, it suffers from rendering glitches that fail to refresh a window's graphical content unless the window is resized.

Safe mode
Safe mode does not log you on due to the login process change in build 4032, as it will result in. This was later fixed in Windows Longhorn build 4042 (main).

Upgrade

 * It is currently not possible to upgrade to this build. After the second reboot, Windows will corrupt the registry and will fail to boot, causing the error  when upgrading from most builds prior to this one.
 * When upgrading from build 4028 ~ build 4033, lsass.exe terminates with a critical error, and the system will become stuck in a bootloop. The only workaround is to reinstall Windows. This bug is persistent until build 4053.