C# How to convert a parent’s hwnd (IntPtr) into NativeWindow that can be used in a Form.Show(nativewindow)

Question

I'm trying to show a dialog over my Credential Provider tile. I call the OnCreatingWindow() method (from CredentialProvider.Interop.dll) which returns the HWND of the appropriate parent window. Before beeing able to use the handle in Form.Show(parentWindow), I need to convert the HWND handle into a NativeWindow implementing IWin32Window. This conversion does not work for me.

I've tried (where parentWndHandle is returned from OnCreatingWindow())

var nativeWindow = new NativeWindow();
nativeWindow.AssignHandle(parentWndHandle);

and

IWin32Window parent = NativeWindow.FromHandle(parentWndHandle);

and

IWin32Window parent = Control.FromHandle(parentWndHandle)

All of them return null

Expected result should be a NativeWindow to parent the dialog I want to show