How can I render some graphics using XNA to a widget/control in a WPF app? Specifically, I don't need any WPF controls inside the XNA graphics window, I just want to put some controls around it for a level editor.
You can use reflection to snag the Direct3D render target handle and hook it up with D3DImage. I've done this successfully with WPF and XNA 3.1, but I had some issues with XNA 4.0 because they changed the surface format mappings. But supposedly other people have gotten it working with XNA 4.0.