Why is Keyboard.FocusedElement null when focus is inside WindowsFormsHost? It breaks WPF command routing

Question

I have a custom RoutedUICommand MyCommand which gets executed via ICommand.Execute. The top window has a binding to handle it:

Answer 1

To complete the interop Form-WPF you need to do this:

App.xaml.cs:

    public partial class App : Application
      {
      protected override void OnStartup(StartupEventArgs e)
        {
        WindowsFormsHost.EnableWindowsFormsInterop();
        base.OnStartup(e);
        }
      }