How can I disable my extensions menu item if the editor doesn't have focus?

How can I disable my extensions menu item if the editor doesn't have focus i.e. first responder? I have a menu item maped to Ctrl+C that I want my extension to handle. But I need xcode to pass the Ctrl+c to the Edit->Copy menu item is any other edit field has focus. I'm preforming additional functionality that's only relivent if your editing in the Standard Editor.