message: Typescript - freeze window.ssf api
diff: @@ -5,6 +5,12 @@ import * as ReactDOM from 'react-dom';
  import WindowsTitleBar from '../renderer/windows-title-bar';
  import { SSFApi } from './ssf-api';
  +interface ISSFWindow extends Window {
  + ssf?: SSFApi;
  +}
  +
  +const ssfWindow: ISSFWindow = window;
  +
  /**
  * creates API exposed from electron.
  */
  @@ -23,7 +29,8 @@ const createAPI = () => {
  // API exposed to renderer process.
  //
  // @ts-ignore
  - window.ssf = new SSFApi();
  + ssfWindow.ssf = new SSFApi();
  + Object.freeze(ssfWindow.ssf);
  };
  createAPI();
  