Issues when customize sorting for TreeListView

[Jane]

I met issues when I try to customize sorting for TreeListView control. Could you please give me some help on these issues? In general, I met 3 major issues:
Issue 1: Click one column header(e.g. "Name" column) -> the sorting is applyed and the small triangle -> Modifiy the name of Item1 as Item4 -> Item4 is not move to the bottom of tree list view.
Issue 2: Click one column header(e.g. "Name" column) -> the sorting is applyed and the small triangle -> Expand one node in tree list view -> the small triangle is not appeared anymore.
Issue 3: First expend all nodes in TreeListView -> Click one column header(e.g. "Name" column) -> All expend nodes are collapsed.

Following are all the codes of my prototype:
ViewModel.cs:

public class ViewModel
{
   public ViewModel()
   {
      Items = new ObservableCollection<ItemVM>();
      InitItems();
   }
   public ObservableCollection<ItemVM> Items { get; set; }
   private void InitItems()
   {
      for (int i = 1; i < 4; i++ )
      {
         ItemVM item = new ItemVM("Item" + i);
         Items.Add(item);
      }
      int index = 1;
      foreach (ItemVM itemvm in Items)
      {
         for (int i = 1; i < 4; i++ )
         {
            ItemVM item = new ItemVM(String.Format("Item{0}-Object{1}",index,i));
            itemvm.Items.Add(item);
         }
         index++;
      }
   }
}
public class ItemVM
{
   public ItemVM(string name)
   {
      this.Name = name;
      Items = new ObservableCollection<ItemVM>();
   }
   public string Name
   {
      get
      {
         return m_cached_name;
      }
      set
      {
         if (m_cached_name != value)
         {
            m_cached_name = value;
         }
      }
   }
   public ObservableCollection<ItemVM> Items { get; set; }
   private String m_cached_name;
}

MainWindow.xaml

<Window xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"  x:Class="RedTreeView_Demo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:RedTreeView_Demo"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <vm:ViewModel x:Key="view_model"/>
    </Window.Resources>
    <Grid>
        <telerik:RadTreeListView Name="RadTreeListView1"
                                 ItemsSource="{Binding Source={StaticResource view_model}, Path=Items}"
                                 Sorting="RadTreeListView1_Sorting">
            <telerik:RadTreeListView.ChildTableDefinitions>
                <telerik:TreeListViewTableDefinition ItemsSource="{Binding Items}"/>
            </telerik:RadTreeListView.ChildTableDefinitions>
            <telerik:RadTreeListView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Name}" Header="Name" />
            </telerik:RadTreeListView.Columns>
        </telerik:RadTreeListView>
    </Grid>
</Window>

MainWindow.xaml.cs

namespace RedTreeView_Demo
{
   /// <summary>
   /// Interaction logic for MainWindow.xaml
   /// </summary>
   public partial class MainWindow : Window
   {
      public MainWindow()
      {
         InitializeComponent();
      }

      private void RadTreeListView1_Sorting(object sender, Telerik.Windows.Controls.GridViewSortingEventArgs e)
      {
         //Gets the value of the ItemSource property
         IEnumerable<ItemVM> ItemVMs = e.DataControl.ItemsSource as IEnumerable<ItemVM>;
         if (ItemVMs == null)
         {
            e.Cancel = true;
            return;
         }

         //If the sorting state is none or descending, sort the items ascending
         if (e.OldSortingState == SortingState.None || e.OldSortingState == SortingState.Descending)
         {
            e.NewSortingState = SortingState.Ascending;
            ItemVMs = ItemVMs.OrderBy(item => item.GetType().GetProperty(e.Column.UniqueName).GetValue(item, null));
            foreach (ItemVM itemVM in ItemVMs)
            {
               IEnumerable<ItemVM> ivms = itemVM.Items as IEnumerable<ItemVM>;
               ivms = ivms.OrderBy(item => item.GetType().GetProperty(e.Column.UniqueName).GetValue(item, null));
               itemVM.Items = new ObservableCollection<ItemVM>();
               foreach (ItemVM item in ivms)
               {

                  itemVM.Items.Add(item);
               }
            }
         }
         //If the sorting state is ascending, sort the items descending
         else if (e.OldSortingState == SortingState.Ascending)
         {
            e.NewSortingState = SortingState.Descending;
            ItemVMs = ItemVMs.OrderByDescending(item => item.GetType().GetProperty(e.Column.UniqueName).GetValue(item, null));
            foreach (ItemVM itemVM in ItemVMs)
            {
               IEnumerable<ItemVM> ivms = itemVM.Items as IEnumerable<ItemVM>;
               ivms = ivms.OrderByDescending(item => item.GetType().GetProperty(e.Column.UniqueName).GetValue(item, null));
               itemVM.Items = new ObservableCollection<ItemVM>();
               foreach (ItemVM item in ivms)
               {
                  itemVM.Items.Add(item);
               }
            }
         }

         //Set the sorted collection as source of the RadTreeListView
         e.DataControl.ItemsSource = ItemVMs.ToList();
         e.Cancel = true;
      }
   }
}

[Jane]

I am using version 2011.1.419.35.
Highly appreciate for any help.

[Ivan Ivanov]

Hello Jane,

I have just posted an answer to your inquiry in the other thread, you have opened. In order to achieve a fruitful and consistent dialogue, I would ask you to carry out any further communication there. Thank you.

Best wishes,
Ivan Ivanov
the Telerik team