...without using the Microsoft Interop Forms Toolkit.

What we do until now: We use the .NET Framework 4.8.1 to write class libraries in C# and expose them to COM using the Interop Forms Toolkit. We call the COM-Server from PowerBuilder 2021. This works fine for invisible classes as well for visible user controls.

What we don't like: The Microsoft Interop Forms Toolkit is super old, and not supported any more.

What we want: Get rid of the toolkit. We want to use the latest .NET Framework (4.8.1) or .NET 8+ with build-in assemblies.

The try: This works super-easy with invisible COM-Servers (see attachment CCWNonVisible.zip).
We wrote an interface, a class which implements the interface. We build the project for x86, set the registration for Interop and use strong names.

But how can i expose a System.Windows.Forms.UserControl to PowerBuilder (see attachment CCWActiveX.zip)? The toolkit adds a manifest. Is this the missing part? 

Many thanks for your ideas!

Btw. i read all the articles i could found for COM Callable Wrappers on the Microsoft sites and all the Bruce Armstrong articles in this Community. Still no idea.