Provide a simple brush/style to use Acrylic and Mica backgrounds in WPF XAML

WPF didn't get the attention like WinForms during the move to open source/.NET 5 and 6. Microsoft is pushing for a more "modern UI" in Windows 10 and especially with Windows 11. It seems that MS is now more focused on polished designs to make the platform attractive again. Providing APIs to use these designs is crucial.

Having these APIs and tools only available in one technology (like UWP) is a huge shortcoming. Even for completely new projects there are plenty of scenarios and use cases where we simply cannot use UWP and need to go "back" to WPF. When we do, we also want to make our app pretty :)

I think it's very important to make sure all the necessary tools and APIs are available for WPF from the beginning to make sure ALL technologies can produce slick, fluent design apps. A brush/style which can easily be used to render the Acrylic/Mica background would be a good first step. Providing a complete WPF "style sheet" to render all common controls according to the fluent design guidelines would also be very welcome.

Here's a project I found on github which tries to accomplish what I mean:
https://github.com/sourcechord/FluentWPF

This should be provided out of the box, from the framework and it should "just work".