Hello,

 A solution to this problem is to presort the data before binding it to the XamOutlookBar. Another way is to add a button in the XamOutlookBar and handle its click event. A quick way to sort the observable collection is like this:

private void buttonSort_Click(object sender, RoutedEventArgs e)
        {

            List<int> temp = observableCollection.ToList();
            observableCollection.Clear();
            temp.Sort();
            foreach (int item in temp)
            {
                observableCollection.Add(item);
            }
            listView.ItemsSource = observableCollection;

        } 

Hope this helps