Is Logical Ancestor Of

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Media;

public static class PopupHelper
{
    public static bool IsLogicalAncestorOf(this UIElement ancestor, UIElement child)
    {
        if (child != null)
        {
            FrameworkElement obj = child as FrameworkElement;
            while (obj != null)
            {
                FrameworkElement parent = VisualTreeHelper.GetParent(obj) as FrameworkElement;
                obj = parent == null ? obj.Parent as FrameworkElement : parent as FrameworkElement;
                if (obj == ancestor) return true;
            }
        }
        return false;
    }
}