How can I make a PropertyEditor's ValueTemplate's control appear like built-in controls?

Background:

I'm adding a PropertyEditor to my PropertyGrid that uses a custom ValueTemplate. The custom DataTemplate contains a ComboBox, which works as desired. However, my custom DataTemplate's ComboBox doesn't match the appearance of a built-in PropertyGrid ComboBox. 

Question:

How can I make my custom template's ComboBox have the same appearance as the PropertyGrid's built-in ComboBox?

Sample Code:

MainWindow.xaml

<Window
    x:Class="PropertyGridCustomTemplates.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:propgrid="http://schemas.actiprosoftware.com/winfx/xaml/propgrid"
    xmlns:Collections="clr-namespace:System.Collections;assembly=mscorlib"
    xmlns:propertyGridCustomTemplates="clr-namespace:PropertyGridCustomTemplates"
    Title="MainWindow" 
    Height="350" 
    Width="525"
    >
    <Window.Resources>
        <!--
        This ComboBox will be empty; I'm just using this to force a custom ComboBox to appear in the PropertyGrid.
        -->   
        <DataTemplate 
            x:Key="bobTemplate"
            >
            <ComboBox
                DisplayMemberPath="Name"
                ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type propgrid:IPropertyDataAccessor}}, Path=DataContext}"
                SelectedValue="{Binding RelativeSource={RelativeSource AncestorType={x:Type propgrid:IPropertyDataAccessor}}, Path=DataContext, ValidatesOnDataErrors=True, Mode=TwoWay}"
                SelectedValuePath="Bob"
                />
        </DataTemplate>

        <Collections:ArrayList
            x:Key="propertyGridEditorsList"
            >
            <propgrid:PropertyEditor
                ObjectType="{x:Type propertyGridCustomTemplates:SampleViewModel}"
                PropertyName="Bob"  
                ValueTemplate="{StaticResource bobTemplate}"
                />
        </Collections:ArrayList>
        
        <propertyGridCustomTemplates:SampleViewModel x:Key="bob"/>
    </Window.Resources>
    <Grid>
        <propgrid:PropertyGrid
            x:Name="propertyGrid"
            SelectedObject="{StaticResource bob}"
            />
    </Grid>
</Window>

MainWindow.xaml.cs:

using System.Collections;
using System.Linq;
using System.Windows;
using ActiproSoftware.Windows.Controls.PropertyGrid.Editors;

namespace PropertyGridCustomTemplates
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            var propEditors = this.Resources["propertyGridEditorsList"] as ArrayList;
            propertyGrid.PropertyEditors.Clear();
            propertyGrid.PropertyEditors.AddRange(propEditors.Cast<PropertyEditor>());
        }
    }
}

 SampleViewModel.cs:

using System.Windows;

namespace PropertyGridCustomTemplates
{
    public class SampleViewModel
    {
        public string Bob { get; set; }

        public HorizontalAlignment Alignment { get; set; }
    }
}

 Thanks,

-Craig