How to change the display level of two UIWindow with same windowLevel ？
UIWindow *windowNormal2 = [[UIWindow alloc] initWithFrame:CGRectMake(40, 40, 100, 200)];
windowNormal2.backgroundColor = [UIColor blueColor];
windowNormal2.windowLevel = UIWindowLevelNormal + 1;
[windowNormal2 makeKeyAndVisible];