Electron Fiddle Gist

index.html

<!-- Empty -->

main.js

// Create native application menus and context menus.
//
// For more info, see:
// https://electronjs.org/docs/api/menu

const { app, BrowserWindow, Menu } = require('electron')

app.on('ready', () => {
  const win1 = new BrowserWindow({ height: 600, width: 600, x:0, y:0 })
  const win2 = new BrowserWindow({ height: 600, width: 600 })
  win1.loadURL('https://stackexchange.com')
  win2.loadURL('https://stackoverflow.com')

  const template = [
    {
      label: 'Edit',
      submenu: [
        { role: 'close' },
        { role: 'quit' },
      ]
    }
  ]

  const menu = Menu.buildFromTemplate(template)
  Menu.setApplicationMenu(menu)
})

preload.js

// Empty

renderer.js

// Empty

styles.css

/* Empty */