             <CollectionViewSource Source="{Binding PersonItems}" x:Key="PersonItemsSource">                     <CollectionViewSource.SortDescriptions>                         <scm:SortDescription PropertyName="DOB" Direction="Descending" />                     </CollectionViewSource.SortDescriptions>                 </CollectionViewSource>                  <ui:DesignPersonViewModel x:Key="DesignTimeViewModel" />         