title: unchecked any one checkbox of CellTemplate from the list, I want to uncheck the Header Checkbox
body: <p>I have created a data table which contains 4 columns, 3 are strings and another one is Boolean type. 
  i mapped the datatable(xmldatadocument) to the datagridview in wpf. 
  so the resulting looks text column and checkbox column in data grid. 
  And i added a checkbox header template to the chekbox column header. 
  I am able to perform uncheck all checkboxes in column when i\the header checkbox is unchecked. 
  I am also able to perform check all checkboxes in column when the header chekcbox is checked.but i am bit troubled in if one of checkbox in that column is unchecked i need to uncheck the header checkbox also.. 
  Kindly help me to resolve this.. 
  i've added the screenshot, XAML and Code below.</p>
  
  <p><img src="https://i.stack.imgur.com/SafCh.jpg" alt="Datagridview"></p>
  
  <p>PS: using WPF datagrid.</p>
  
  <pre><code>&lt;dg:DataGrid.Columns&gt;
                  &lt;dg:DataGridCheckBoxColumn Binding="{Binding Check}" Width="50" &gt;
                      &lt;dg:DataGridCheckBoxColumn.HeaderTemplate&gt;
                          &lt;DataTemplate x:Name="dtAllChkBx"&gt;
                              &lt;CheckBox Name="cbxAll" Content="{x:Static properties:Resources.lblAll}" Checked="CheckBox_Checked" Unchecked="CheckBox_Unchecked"&gt;&lt;/CheckBox&gt;
                          &lt;/DataTemplate&gt;
                      &lt;/dg:DataGridCheckBoxColumn.HeaderTemplate&gt;
  
  
  public static ObservableCollection&lt;Lst&gt; list = new ObservableCollection&lt;Lst&gt;();
  private void CheckBox_Checked(object sender, RoutedEventArgs e)
  {
      for (int i = 0; i &lt; list.Count; i++)
      {
          list[i].Check = true;
      }
  }
  
  private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
  {
      for (int i = 0; i &lt; list.Count; i++)
      {
          list[i].Check = false;
      }
  }
  
  public class Lst : ObservableCollection&lt;Lst&gt;
  {
      public bool Check { get; set; }
  }  
  </code></pre>