c# WPF transparency over Winform controls

Question

I have a WPF control that I would like to overlay onto a WinForms application. So I have dutifully created a Element Host that can show the following WPF object:

Answer 1

I think you're running into an airspace issue. AFAIK, you can't mix WPF transparency and ElementHost transparency since the ElementHost owns the airspace.

There's a short blurb in the link about creating non-rectangular hwnds to host WPF content, and that may get you farther.

Perhaps you can consider migrating more of the WinForms app to WPF?