[Feature Request]: allow BrowserWindow to be created maximized or fullscreen

[bpasero]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

You cannot pass options to a window to open it maximized or fullscreen, so you have to call maximize or setFullscreen after the window is already opened. This results in an ugly flicker as demonstrated below:

I am aware of the ready-to-show event, but that event is not even recommended for very large apps (such as VS Code).

As a workaround we currently set show: false and then call window.maximize and window.show. But we would like to drop this workaround.

Proposed Solution

The BrowserWindow constructor allows to pass in an option that the window is either maximized or fullscreen when being created.

Alternatives Considered

Hiding the window on creation is our current workaround but it is brittle, as #32949 (comment) shows.

Additional Information

main.js code:

// Modules to control application life and create native browser window
const { app, BrowserWindow } = require('electron')
const path = require('path')

function createWindow() {
  // Create the browser window.
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    show: true,
    webPreferences: {
      preload: path.join(__dirname, 'preload.js')
    }
  })

  mainWindow.maximize();

  // and load the index.html of the app.
  mainWindow.loadFile('index.html')

  setTimeout(() => {
    const mainWindow = new BrowserWindow({
      width: 800,
      height: 600,
      show: true,
      webPreferences: {
        preload: path.join(__dirname, 'preload.js')
      }
    })

    mainWindow.maximize();
    mainWindow.loadFile('index.html')
  }, 2000)

  // Open the DevTools.
  // mainWindow.webContents.openDevTools()
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(() => {
  createWindow()

  app.on('activate', function () {
    // On macOS it's common to re-create a window in the app when the
    // dock icon is clicked and there are no other windows open.
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

// In this file you can include the rest of your app's specific main process
// code. You can also put them in separate files and require them here.