This is a vague memory so I might be wrong, but I think it's WinForms, not WPF, and it makes calls into Windows directly using P/Invoke so it's not trivially portable.
Both WPF and WinForms, additionally at least DirectWrite and Direct2D and by now a bunch of shader code for the various effects. I guess there's a lot of things that can go wrong when trying to run it via Wine.
