A Reusable WPF Autocomplete TextBox (Part 2)

namespace Aviad.WPF.Controls
{
  using System.Windows;
  using System.Windows.Controls;
  using System.Windows.Input;

  public static class ListBoxItemBehavior
  {
    #region fields
    // Using a DependencyProperty as the backing store for SelectOnMouseOver.
    // This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectOnMouseOverProperty =
        DependencyProperty.RegisterAttached("SelectOnMouseOver",
                                             typeof(bool),
                                             typeof(ListBoxItemBehavior),
                                             new UIPropertyMetadata(false, OnSelectOnMouseOverChanged));
    #endregion fields

    #region methods
    public static bool GetSelectOnMouseOver(DependencyObject obj)
    {
      return (bool)obj.GetValue(SelectOnMouseOverProperty);
    }

    public static void SetSelectOnMouseOver(DependencyObject obj, bool value)
    {
      obj.SetValue(SelectOnMouseOverProperty, value);
    }

    private static void OnSelectOnMouseOverChanged(DependencyObject d,
                                           DependencyPropertyChangedEventArgs e)
    {
      ListBoxItem lbi = d as ListBoxItem;
      if (lbi == null) return;

      bool bNew = (bool)e.NewValue, bOld = (bool)e.OldValue;

      if (bNew == bOld) return;

      if (bNew)
        lbi.MouseEnter += new MouseEventHandler(lbi_MouseEnter);
      else
        lbi.MouseEnter -= lbi_MouseEnter;
    }

    private static void lbi_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e)
    {
      ListBoxItem lbi = (ListBoxItem)sender;
      lbi.IsSelected = true;
      var listBox = ListBox.ItemsControlFromItemContainer(lbi);

      FrameworkElement focusedElement =
                (FrameworkElement)FocusManager.GetFocusedElement(FocusManager.GetFocusScope(listBox));

      if (focusedElement != null && focusedElement.IsDescendantOf(listBox))
        lbi.Focus();
    }
    #endregion fields
  }
}