title: how to bind the Tag Properties of the textbox that placed in the DataGridColumnHeadertemplate to DataGridTextColumn.Name?
body: <p>i have a textBox(txtSearch) placed in a DataGridColumnHeadertemplate like this:</p>
  
  <pre><code> &lt;UserControl.Resources&gt;
   &lt;Style x:Key="DataGridColumnHeaderStyle1" TargetType="{x:Type DataGridColumnHeader}"&gt;
              &lt;Setter Property="Template"&gt;
                  &lt;Setter.Value&gt;
                      &lt;ControlTemplate TargetType="{x:Type DataGridColumnHeader}"&gt;
                          &lt;Grid VerticalAlignment="Center" HorizontalAlignment="Stretch"&gt;
                              &lt;Grid.RowDefinitions&gt;
                                  &lt;RowDefinition Height="*"/&gt;
                                  &lt;RowDefinition Height="*"/&gt;
                              &lt;/Grid.RowDefinitions&gt;
                              &lt;TextBlock Grid.Row="0" Text="{TemplateBinding Content}" HorizontalAlignment="Center" /&gt;
                              &lt;Grid Grid.Row="1" &gt;
                              &lt;TextBox x:Name="txtSearch" Tag="{Binding DataGridTextColumn.Name, ElementName=grd}"  Text="" HorizontalAlignment="Stretch"  BorderThickness="1" TextChanged="TextBox_TextChanged" /&gt;
                              &lt;/Grid&gt;
                          &lt;/Grid&gt;
                      &lt;/ControlTemplate&gt;
                  &lt;/Setter.Value&gt;
              &lt;/Setter&gt;
          &lt;/Style&gt;
      &lt;/UserControl.Resources&gt;
  </code></pre>
  
  <p>and use it for a datagrid like this:</p>
  
  <pre><code> &lt;DataGrid x:Name="grd" ItemsSource="{Binding Source={StaticResource theSource}}" AutoGenerateColumns="False"  ColumnHeaderStyle="{DynamicResource DataGridColumnHeaderStyle1}"&gt;
          &lt;DataGrid.Columns &gt;
              &lt;DataGridTextColumn Header="نام" Binding="{Binding Title}" x:Name="Title" &gt;&lt;/DataGridTextColumn&gt;
              &lt;DataGridTextColumn Header="ID" Binding="{Binding ParentID}" x:Name="ParentID"&gt;&lt;/DataGridTextColumn&gt;
          &lt;/DataGrid.Columns&gt;
      &lt;/DataGrid&gt;
  </code></pre>
  
  <p>and now i need to bind the txtSearch Tag properties to DataGridTextColumn.Name.how can i do that?</p>