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If they switch to the open source & cross platform .Net Core, then the 'Unified' app UI is possible. http://dotnet.github.io/core/

The UI looks doable with WPF. I would love to see the code and learn from it

If it's using WPF, does that mean that it requires .NET?

Yep. Though AFAIK .NET is included with Windows these days

They're still using WPF on Windows.