Solution: hide default titlebar or customize it at MacOS

[Moosphan]

Here provide two different ways to realize it.

1. Xcode configs by hand

e.g. https://medium.com/flutter-community/transparent-title-bar-on-macos-with-flutter-7043d44f25dc

2. Flutter way

Go your project dir/macos/Runner/MainFlutterWindow.swift:

import Cocoa
import FlutterMacOS

class MainFlutterWindow: NSWindow {
  override func awakeFromNib() {
    let flutterViewController = FlutterViewController.init()
    let windowFrame = self.frame
    self.contentViewController = flutterViewController
    self.setFrame(windowFrame, display: true)

+     // Hide system icon buttons in the title bar.
+     self.standardWindowButton(.closeButton)?.isHidden = true
+    self.standardWindowButton(.miniaturizeButton)?.isHidden = true
+    self.standardWindowButton(.zoomButton)?.isHidden = true

    RegisterGeneratedPlugins(registry: flutterViewController)

    super.awakeFromNib()
  }
}