Blend “Window is not supported in a WPF Project”

Question

I am having a frustrating time with Blend reporting \"Window is not supported in a Windows Presentation Foundation (WPF) project.\" due to unbuildable configurations but can\'t

Answer 1

Blend requires the solution to ALSO have an AnyCPU platform in the configuration manager.
Any C++ (including C++/CLI) projects in the solution will not be loaded.

I have AnyCPU +x86 +x64 platforms in my solutions, the AnyCPU doesn't build non C# projects.

Put the windows/controls in AnyCPU C# dlls, so they can be edited in blend.
(Do not reference x86/x64 projects from them.)

Set the exe as x86 and x64 only (no AnyCPU) - will not run in blend (no AnyCPU), but the solution will still build.