title: Get SelectedItem from TreeView?
body: <p>Does anyone know how I can get the SelectedItem (not the Header) from a TreeView?<br>
  Here is my code:</p>
  
  <pre><code>&lt;TreeView Name="treeView1" DataContext="{Binding Path=PresentationsViewModel}" Grid.Column="1" &gt;
      &lt;TreeViewItem IsExpanded="True" Header="Objects-A-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListA}"&gt;&lt;/TreeViewItem&gt;
      &lt;TreeViewItem IsExpanded="True" Header="Objects-B-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListB}"&gt;&lt;/TreeViewItem&gt;
      &lt;TreeViewItem IsExpanded="True" Header="Objects-C-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListC}"&gt;&lt;/TreeViewItem&gt;
  &lt;/TreeView&gt;
  </code></pre>
  
  <p>Note that there are 3 different Lists, containing 3 different Object-Types.
  It'd help me a lot to have something like:  </p>
  
  <pre><code>public Object SelectedObject
  {
      set { _selectedObject = value; RunMyMethod(); RaisePropertyChanged("SelectedObject"); }
  }  
  </code></pre>