public void TestDoubleRemove()
        {
            var menu = new NavigationMenu();

            var child = new ContentPage {
                Icon    = "jpg.jpg",
                Content = new View()
            };

            menu.Add(child);
            menu.Remove(child);

            bool signaled = false;

            menu.PropertyChanged += (sender, args) => {
                switch (args.PropertyName)
                {
                case "Targets":
                    signaled = true;
                    break;
                }
            };

            menu.Remove(child);

            Assert.False(menu.Targets.Contains(child));
            Assert.False(signaled);
        }