wpf DataGridComboBoxColumn

<Window x:Class="WpfApplication5.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApplication5"
xmlns:system="clr-namespace:System;assembly=mscorlib"
mc:Ignorable="d"
Title="MainWindow" Name="this" Height="556" Width="851">

<StackPanel>

<DataGrid ItemsSource="{Binding Path=SelectedList,ElementName=this}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Header="文本模式" Binding="{Binding Path=Value}" />
<DataGridComboBoxColumn Header="ComboBox模式" SelectedValueBinding="{Binding Path=Value}" ItemsSource="{Binding Path=SelectionList,ElementName=this}" />
<DataGridTemplateColumn Header="Template模式">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox SelectedValue="{Binding Path=Value}" ItemsSource="{Binding Path=SelectionList ,ElementName=this}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridComboBoxColumn Header="ComboBox模式（修正）">
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox">
<Setter Property="ItemsSource" Value="{Binding Path=SelectionList,ElementName=this}" />
<Setter Property="SelectedValue" Value="{Binding Path=Value,UpdateSourceTrigger=PropertyChanged}"/>
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
<DataGridComboBoxColumn.ElementStyle>
<Style TargetType="ComboBox">
<Setter Property="ItemsSource" Value="{Binding Path=SelectionList,ElementName=this}" />
<Setter Property="SelectedValue" Value="{Binding Path=Value}"/>
</Style>
</DataGridComboBoxColumn.ElementStyle>
</DataGridComboBoxColumn>
</DataGrid.Columns>
</DataGrid>
<Button Content="观察选中的数据" Click="Button_Click" Margin="10"/>
<TextBox Name="TBX_Selected" />
</StackPanel>
</Window>

public class DataItem
{
public int Value { get; set; }
public DataItem(int val) { Value = val; }
}

public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();

SelectedList.Add(new DataItem(1));
SelectedList.Add(new DataItem(2));
SelectedList.Add(new DataItem(3));
SelectedList.Add(new DataItem(3));
SelectedList.Add(new DataItem(3));
SelectedList.Add(new DataItem(3));
SelectedList.Add(new DataItem(3));
// 可选数据
SelectionList.Add(1);
SelectionList.Add(2);
SelectionList.Add(3);
}
public ObservableCollection<int> SelectionList
{
get { return _selectionList; }
set { _selectionList = value; }
}
private ObservableCollection<int> _selectionList = new ObservableCollection<int>();
public ObservableCollection<DataItem> SelectedList
{
get { return _selectedList; }
set { _selectedList = value; }
}
private ObservableCollection<DataItem> _selectedList = new ObservableCollection<DataItem>();
private void Button_Click(object sender, RoutedEventArgs e)
{
TBX_Selected.Text = "";
foreach (var item in SelectedList)
TBX_Selected.Text += item.Value.ToString(" --->0<--- ");
}
}