title: WPF Treeview updating
body: <p>I have to treeviews in a window. Both treeview are bound to an observable collection "ReportStructure".</p>
  
  <p>Both treeviews shows a treelevel hierarcical structure of the observable collection. I use one treeview, T1. to select the nodes i want to show in the second treeview T2.</p>
  
  <p>The first treeview has checkboxes on each leaf and when i check or uncheck a leaf it is shown or hidden in T2. In order for me to do that i have to requery the bound collectionview like this</p>
  
  <pre><code>  var IEquip = from eq in Report.Document.InspectionData.Equipments where eq.PartData.ReportIncluded = true
                       orderby eq.PartData.Order ascending
                       select eq;
  
  
          EquipmentView = CollectionViewSource.GetDefaultView(IEquip);
          EquipmentView.SortDescriptions.Add(
         new SortDescription("PartData.Order", ListSortDirection.Ascending));  
  </code></pre>
  
  <p>The "ReportStructure" above is Report.Document.InspectionData.Equipments.</p>
  
  <p>My problem is that when i requery the datacontext for T2 all nodes in T1 are collapsed</p>
  
  <p>I my XAML i have set updatesourcetrigger explicit but it still collapses.</p>
  
  <pre><code>    &lt;TreeView Grid.Row="5" IsEnabled="True" HorizontalContentAlignment="Stretch" Background="Transparent" BorderThickness="0"
      ItemsSource="{Binding ReportStructure, UpdateSourceTrigger=Explicit}"   HorizontalAlignment="Stretch"  /&gt;
  </code></pre>
  
  <p>Cloning would be a solution, but then i loose the possiblity to update T2 from the information in T1 without passing the clone</p>