Officially, it isn't (e.g. it got ported to .NET Core). De facto, it is, but it still works just fine, as do WinForms, and all the tooling support is still there.

That said, I've mentioned WPF mostly because that's what I'm personally familiar with. The same inspector-type tooling is available for newer XAML-based frameworks, as well:

https://docs.microsoft.com/en-us/visualstudio/xaml-tools/ins...