Reversibly enable and disable Windows Classic theme using PowerShell

[Anixx]

Here is a method which allows to enable and disable Classic Theme during one session from the command line. Tested on Windows 8.1.
Enabling or disabling the Classic theme affects only programs started after the change. This method is different from other methods in that it is reversible: one can multiple times enable and disable theming via a task, shortcut or a bat file.

Steps:

1. Install PowerShell 6:

github.com/PowerShell/PowerShell/releases/download/v6.2.1/PowerShell-6.2.1-win-x64.msi

github.com/PowerShell/PowerShell/releases/download/v6.2.1/PowerShell-6.2.1-win-x86.msi

2. Run PowerShell 6 and type:

Install-Module -Name NtObjectManager

3. Now you can enable and disable Classic Theme.

To enable, open elevated command prompt and type:

pwsh -c Set-NtSecurityDescriptor -path \"\Sessions\$([System.Diagnostics.Process]::GetCurrentProcess().SessionId)\Windows\ThemeSection\" \"O:BAG:SYD:(A;;RC;;;IU)(A;;DCSWRPSDRCWDWO;;;SY)\" Dacl

To disable, open elevated command prompt and type:

pwsh -c Set-NtSecurityDescriptor -path \"\Sessions\$([System.Diagnostics.Process]::GetCurrentProcess().SessionId)\Windows\ThemeSection\" \"O:BAG:SYD:(A;;CCLCRC;;;IU)(A;;CCDCLCSWRPSDRCWDWO;;;SY)\" Dacl