Get application object outside of activate method?

Hi, I am writing a front end plugin where I need the application object (app: JupyterFrontEnd) in a certain function. Currently, I am defining the function as a closure inside my activate function:

const plugin: JupyterFrontEndPlugin<void> = {
  id: 'myfancy:plugin'
  // ...
  activate: (
    app: JupyterFrontEnd,
    toolbarRegistry: IToolbarWidgetRegistry | null,
    // ...
  ) => {

    const createStatusWidget = (panel: NotebookPanel) => {
      // do something with app in here
    }

    toolbarRegistry.registerFactory<NotebookPanel>(
        'Notebook', 'mydemo', createStatusWidget
    );
  }
}

Is there a way to get app from somewhere else, for example from the NotebookPanel object or from a global function? Then I could factor functions like this out of my activate method.

I guess I could add a parameter app to createStatusWidget, and then use small lambda, but maybe there is a simpler solution:

toolbarRegistry.registerFactory<NotebookPanel>(
    'Notebook', 'mydemo', panel => createStatusWidget2(app, panel)
);