I'm getting started working with [Electron](http://electron.atom.io) to build a desktop app. How can I customize the window title bar (which contains the close, minimize, and full screen buttons) to add custom views? Safari is an example that I am thinking of:

[![safar title bar](https://i.stack.imgur.com/xgS3S.png)](https://i.stack.imgur.com/xgS3S.png)