import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

  @IBOutlet weak var window: NSWindow!


  func applicationDidFinishLaunching(_ aNotification: Notification) {
    // Insert code here to initialize your application
  }

  func applicationWillTerminate(_ aNotification: Notification) {
    // Insert code here to tear down your application
  }
}

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

  var window: NSWindow?

  func applicationDidFinishLaunching(_ notification: Notification) {
    window = NSWindow()
    window?.styleMask = [.borderless]
    window?.makeKeyAndOrderFront(nil)
  }
}

Refactor applicationDidFinishLaunching to draw a small window on the screen
Refactor applicationDidFinishLaunching to draw a small window on the screen
