[VGA] Shudown winlogon background stretch the desktop in VGA Mode.

ReactOS ver: reactos-bootcd-0.4.15-dev-5921-gefe7368
Arch: Both (x86 or x64)
Compiler: Both (gcc or msvc)
CD type: BootCD - I guess it's also reproducible under LiveCD, I didn't try.

Steps to reproduce:
1. Install ReactOS with the VGA Display (640x480x4) option. (Device type step in the First Stage of the setup).
2. Finish the full ROS installation.
3. Enable the VGA mode in Freeloader v3.0 with F8.
4. Once the system started (with no icons CORE-11393), click Start and select "Shut down the system"

Expected: Proportions are usual when the background is greyed.

Reaction: The background is being stretched.

Debug log: VGA-Bug-Shutdown.log