WPF

<data:DataGridTemplateColumn x:Key="EmployeeIdColumn"
                             Header="Employee ID"
                             Width="Auto" CanUserSort="True"
                             SortMemberPath="EmployeeId">

<data:DataGridTemplateColumn x:Key="EmployeeIdColumn"
                             Header="Employee ID"
                             TooltipService.Tooltip="The employee's ID"   <-- Tooltip
                             Width="Auto" CanUserSort="True"
                             SortMemberPath="EmployeeId">

[Serializable]
   [DataContract(Name = "A", Namespace = "")]
   [KnownType(typeof(B))]
   public class A
   {
       public A()
       {
           Id = 0;
           b = new B();
       }

       [Key]
       [DataMember]
       public int Id { get; set; }

       [DataMember]
       public B b { get; set; }

   }

   [Serializable]
   [DataContract(Name = "B", Namespace = "")]
   public partial class B : ComplexObject
   {
       public B()
       {
           Id = 0;
           Description = string.Empty;
       }

       [Key]
       [DataMember]
       public int Id { get; set; }

       [DataMember]
       public string Description { get; set; }

   }

/// <summary>
   /// The 'A' entity class.
   /// </summary>
   [DataContract(Namespace="", Name="A")]
   public sealed partial class A : Entity
   {

       private int _id;

       #region Extensibility Method Definition

       #endregion

<HierarchicalDataTemplate DataType="{x:Type models:NodeModel}"
                            ItemsSource="{Binding Path=Children}">
    <StackPanel Orientation="Horizontal"
                Margin="2">

        <TextBlock Margin="0,0,5,0">
            <Hyperlink NavigateUri="{Binding Caption}"
                        Foreground="#0C2DAA"
                        Command="{Binding Path=DataContext.SelectedLinkCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={ x:Type views:ProjectListView}}}">
.
.
.

private ICommand _SelectedLinkCommand;
public ICommand SelectedLinkCommand
{
    get
    {
        if (_SelectedLinkCommand == null)
            _SelectedLinkCommand = new RelayCommand(SelectedLinkExecuted, SelectedLinkCanExecute);
        return _SelectedLinkCommand;
    }
}

private bool SelectedLinkCanExecute()
{
    return true;
}
private void SelectedLinkExecuted()
{
    // Get node object here
}