title: To create a new UIWindow over the main window
body: <p>In my app I want to create a new <code>UIWindow</code> over the main UIWindow, And I wrote as following, but it don't works.
  first, i create a <code>UIWindow</code> as the main window, and then make it key and visible, and then create a new <code>UIWindow</code> overlay, but nothing happens.</p>
  
  <pre><code>- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
  {
      self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
      self.window.backgroundColor = [UIColor redColor];
      ViewController *vc = [[ViewController alloc]initWithNibName:@"ViewController" bundle:nil];
      self.window.rootViewController = vc;
      [self.window makeKeyAndVisible];
      UIWindow *window1 = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 320)];
      window1.backgroundColor = [UIColor redColor];
      window1.windowLevel = UIWindowLevelAlert;
      [window1 makeKeyAndVisible];
      return YES;
  }
  </code></pre>