wpf datagrid tooltip

  <DataGridTemplateColumn Header="购方名称" Width="260" HeaderStyle="{StaticResource DataGridColumnHeaderStyle1}">
                                    <DataGridTemplateColumn.CellTemplate>
                                        <DataTemplate>
                                            <TextBlock Text="{Binding DisplayName}">
                                                <TextBlock.ToolTip>
                                                    <StackPanel>
                                                        <TextBlock Text="{Binding DisplayDetail}"/> 
                                                    </StackPanel>
                                                </TextBlock.ToolTip>
                                            </TextBlock>
                                        </DataTemplate>
                                    </DataGridTemplateColumn.CellTemplate>
                                </DataGridTemplateColumn>