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