test.xaml

treectxtest.py

import clr
clr.AddReference("PresentationCore")  
clr.AddReference("PresentationFramework")  
clr.AddReference("WindowsBase")  
clr.AddReference('GalaSoft.MvvmLight.WPF4.dll')


from System.Windows.Markup import XamlReader
from System.Windows import Application
from System.Windows import MessageBox
from System.IO import File
from System.Windows.Controls import TreeView
import System
import clrtype
from GalaSoft.MvvmLight import ViewModelBase
from GalaSoft.MvvmLight.Command import RelayCommand
from System.Collections.ObjectModel import ObservableCollection



class TestModel(ViewModelBase):
   __metaclass__ = clrtype.ClrClass
   def __init__(self):
       self.name = 'algo'
       self.root = NodeModel('x1',[NodeModel('y2',[NodeModel('z2',[])]),
                                   NodeModel('y3',[])])
       self.sselected = NodeModel('???',[])

   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def selected(self): 
      print('rra ' )
      result = self.sselected
      print('rra 2' )
      return result

   @selected.setter
   @clrtype.accepts(System.Object)
   @clrtype.returns()
   def selected(self, value):
      print('xxx ')
      self.sselected = value
      #self.RaisePropertyChanged('selected')
      print('3xxx')
  

   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def Roots(self): 
      return [self.root]


   @property
   @clrtype.accepts()
   @clrtype.returns(System.String)
   def Label(self): 
      print('a')
      return self.name
 
   @Label.setter
   @clrtype.accepts(System.String)
   @clrtype.returns()
   def Label(self, value):
      print('b')
      self.name = value
      print('c')
      self.RaisePropertyChanged('Label')
      print('d')



class MenuItemOptionModel:
   __metaclass__ = clrtype.ClrClass
   def __init__(self,header, action):
      self.header = header
      self.action = action


   @property
   @clrtype.accepts()
   @clrtype.returns(System.String)
   def header_text(self): 
      return self.header

   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def ctxt_action(self): 
      return self.action


class NodeModel:
   __metaclass__ = clrtype.ClrClass

   def __init__(self,label, initchildren):
      self.children = ObservableCollection[System.Object](initchildren)
      self.name = label
      self.menu_items_col = [MenuItemOptionModel('One', RelayCommand(lambda: MessageBox.Show(self.name)))]


   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def Label(self): 
      return self.name

   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def menu_items(self): 
      return self.menu_items_col


   @property
   @clrtype.accepts()
   @clrtype.returns(System.Object)
   def Children(self): 
      return self.children
 

xamlFile = File.OpenRead('test.xaml')
window = XamlReader.Load(xamlFile)
window.DataContext = TestModel()
xamlFile.Close()

Application().Run(window)

utils.cs

using System.Windows.Markup;
using System.Windows;
using System.Windows.Controls;
using System.IO;
using GalaSoft.MvvmLight;
using System.Collections.ObjectModel;


namespace Langexplr 
{

   public static class TreeViewSelectedBehavior
   {
      public static readonly DependencyProperty MySelectedProperty = 
             System.Windows.DependencyProperty.RegisterAttached(
                                       "MySelected",
                                       typeof(object),
                                       typeof(TreeViewSelectedBehavior)
                                    );
      public static object GetMySelected(TreeView t)
      {
          System.Console.WriteLine("1z");
         return t.GetValue(MySelectedProperty);
          System.Console.WriteLine("1z");
      }

      public static void SetMySelected(TreeView t, object theValue)
      {
          System.Console.WriteLine("1y");
         t.SetValue(MySelectedProperty, theValue);
          System.Console.WriteLine("1y");
      }

                                    
      public static readonly DependencyProperty SelectedHelperProperty =
             System.Windows.DependencyProperty.RegisterAttached(
                                       "SelectedHelper",
                                       typeof(TreeViewSelectedHelper),
                                       typeof(TreeViewSelectedBehavior),
                                       new UIPropertyMetadata(null,OnSelectedHelperChanged)
                                    );

      public static  TreeViewSelectedHelper GetSelectedHelper(TreeView t) 
      {
          return (TreeViewSelectedHelper)t.GetValue(SelectedHelperProperty);
      }

      public static void SetSelectedHelper(TreeView t, 
                                           TreeViewSelectedHelper theValue) 
      {
          t.SetValue(SelectedHelperProperty, theValue);
      }
      static void OnSelectedHelperChanged(
                    DependencyObject depObj, 
                    DependencyPropertyChangedEventArgs e)
      {
          System.Console.WriteLine("1x");

         ((TreeViewSelectedHelper)e.NewValue).Register((TreeView)depObj);
          System.Console.WriteLine("2x");
      }

   }

   public class TreeViewSelectedHelper 
   {
       public TreeViewSelectedHelper() {System.Console.WriteLine("Created"); }
       void SelectedItemChanged(object sender, 
                                RoutedPropertyChangedEventArgs<object> args)
       {
          System.Console.WriteLine("1");
           (sender as TreeView).SetValue(TreeViewSelectedBehavior.MySelectedProperty,((sender as TreeView)).SelectedItem);
          System.Console.WriteLine("2");
           
       }
       public void Register(TreeView t)
       {
           t.SelectedItemChanged += SelectedItemChanged;
       }
   }

}

Wpf tree with context menu

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:utils="clr-namespace:Langexplr;assembly=utils"
        Title="Little query" Width="300" Height="300">
   <Window.Resources>
     <utils:TreeViewSelectedHelper x:Key="selHelper" />
   </Window.Resources>
   <StackPanel>

      <TextBlock Text="??"/> 
         <TreeView ItemsSource="{Binding Roots}" 
                   utils:TreeViewSelectedBehavior.SelectedHelper="{StaticResource selHelper}">
             <utils:TreeViewSelectedBehavior.MySelected>
               <Binding Path="selected" Mode="OneWayToSource"/> 
             </utils:TreeViewSelectedBehavior.MySelected> 
	     <TreeView.ItemContainerStyle>
	       <Style  TargetType="TreeViewItem">
		 <Setter Property="ContextMenu">
		   <Setter.Value>
		     <ContextMenu ItemsSource="{Binding menu_items}">
		       <ContextMenu.ItemContainerStyle>
			 <Style TargetType="MenuItem">
			   <Setter Property="Command" Value="{Binding ctxt_action}"/>
			 </Style>
		       </ContextMenu.ItemContainerStyle>
		       <ContextMenu.ItemTemplate>
			 <DataTemplate>
			   <TextBlock Text="{Binding header_text}"/>
			 </DataTemplate>
		       </ContextMenu.ItemTemplate>
		     </ContextMenu>
		   </Setter.Value>
		 </Setter>
	       </Style>

	     </TreeView.ItemContainerStyle>
	     <TreeView.ItemTemplate>
	       <HierarchicalDataTemplate ItemsSource="{Binding Children}">
		 <!--		     <HierarchicalDataTemplate.ItemContainerStyle>

</HierarchicalDataTemplate.ItemContainerStyle>-->
		     <TextBlock Text="{Binding Label}">
		     </TextBlock>
		  </HierarchicalDataTemplate>
	      </TreeView.ItemTemplate>
         </TreeView>
      <Button>Ok</Button>
   </StackPanel>
</Window>