IWindowPrivate

RE'd for you so you can enable window transparency for (UWP) XAML Islands

If you are using Windows Runtime Projectors (C#/WinRT (.NET 5), C++/WinRT, Rust/WinRT, etc..) use IWindowsPrivate.winmd.

For .NET Core 3.0 or older (including "UWP .NET") use IWindowsPrivate.cs. This is because you can't use winmd that has namespaces that starts with "Windows.".

Usage example:

C#

((Window.Current as object) as IWindowPrivate).TransparentBackground = true;

C++/WinRT

Window::Current().as<IWindowPrivate>().TransparentBackground(true);