[WPF] Automatic rows in Grid

AutoGrid.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;

namespace WpfApplication1
{
    public class AutoGrid : Grid
    {
        public static readonly DependencyProperty GeneratedRowStyleProperty =
            DependencyProperty.Register("GeneratedRowStyle", typeof (Style), typeof (AutoGrid), new PropertyMetadata(default(Style)));

        public Style GeneratedRowStyle
        {
            get { return (Style) GetValue(GeneratedRowStyleProperty); }
            set { SetValue(GeneratedRowStyleProperty, value); }
        }

        public static readonly DependencyProperty GeneratedRowProperty =
            DependencyProperty.RegisterAttached("GeneratedRow", typeof (int), typeof (AutoGrid), new PropertyMetadata(default(int)));

        protected static void SetGeneratedRow(UIElement element, int value)
        {
            element.SetValue(GeneratedRowProperty, value);
        }

        public static int GetGeneratedRow(UIElement element)
        {
            return (int) element.GetValue(GeneratedRowProperty);
        }

        private int lastRow = 0;
        protected override void OnVisualChildrenChanged(System.Windows.DependencyObject visualAdded, System.Windows.DependencyObject visualRemoved)
        {
            base.OnVisualChildrenChanged(visualAdded, visualRemoved);
            if (visualAdded != null)
            {
                if (visualAdded is AutoGridEndRow)
                    lastRow++;

                EnsureEnoughRows();

                if (IsDefaultValue(visualAdded, RowProperty))
                {
                    visualAdded.SetValue(GeneratedRowProperty, lastRow);
                    visualAdded.SetCurrentValue(RowProperty, lastRow);
                }

                var dpd = DependencyPropertyDescriptor.FromProperty(RowProperty, visualAdded.GetType());
                dpd.AddValueChanged(visualAdded, OnChildRowChanged);
            }
            if (visualRemoved != null)
            {
                var dpd = DependencyPropertyDescriptor.FromProperty(RowProperty, visualAdded.GetType());
                dpd.RemoveValueChanged(visualAdded, OnChildRowChanged);
            }
        }

        private static bool IsDefaultValue(DependencyObject o, DependencyProperty property)
        {
            return DependencyPropertyHelper.GetValueSource(o, property).BaseValueSource == BaseValueSource.Default;
        }

        private void OnChildRowChanged(object sender, EventArgs ev)
        {
            var element = (UIElement) sender;
            // Restore generated row value if row property is cleared
            if (IsDefaultValue(element, RowProperty) && !IsDefaultValue(element, GeneratedRowProperty))
                element.SetCurrentValue(RowProperty, GetGeneratedRow(element));
            EnsureEnoughRows();
        }

        private void EnsureEnoughRows()
        {
            foreach (UIElement child in Children)
            {
                lastRow = Math.Max(lastRow, GetRow(child));
            }
            for (int i = RowDefinitions.Count; i < lastRow + 1; i++)
            {
                var newRow = new RowDefinition();
                if (GeneratedRowStyle != null)
                    newRow.SetCurrentValue(StyleProperty, GeneratedRowStyle);
                RowDefinitions.Add(newRow);
            }
        }
    }

    public class AutoGridEndRow : UIElement
    {
        public AutoGridEndRow()
        {
            Visibility = Visibility.Collapsed;
        }
    }
}

Window1.xaml

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:my="clr-namespace:WpfApplication1"
        Title="Window1"
        Height="300"
        Width="300">
  <my:AutoGrid>
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="65" />
      <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
    <Label Content="Label1" />
    <TextBox Grid.Column="1" />
    <my:AutoGridEndRow />
    <Label Content="Label1" />
    <TextBox Grid.Column="1" />
  </my:AutoGrid>
</Window>

In lines 42 to 46 you check visualRemoved for null, but then continue to work on visualAdded. Copy & paste error or intention?