public MultiSelectionTestsViewModel()
        {
            AllItems = new XamlObservableCollectionEx<int>();
            SelectedItems = new XamlObservableCollectionEx<int>();

            for (int i = 0; i < 100; i += 2)
            {
                AllItems.Add(i);
            }
        }
        public DragAndDropTestsViewModel()
        {
            OddNumbers = new XamlObservableCollectionEx<int>();
            EvenNumbers = new XamlObservableCollectionEx<int>();

            for (int i = 0; i < 100; i += 2)
            {
                EvenNumbers.Add(i);
                OddNumbers.Add(i + 1);
            }
        }