Checkbox Header in Datagrid

                    <sdk:DataGridTemplateColumn Width="47" >
                           <sdk:DataGridTemplateColumn.HeaderStyle>
                                <Style TargetType="sdk:DataGridColumnHeader">
                                    <Setter Property="ContentTemplate">
                                        <Setter.Value>
                                            <DataTemplate>
                                                <CheckBox HorizontalAlignment="Center" Margin="10,0,0,0"  Name="Chk" Checked="Chk_Checked" Unchecked="Chk_Unchecked"></CheckBox>
                                            </DataTemplate>
                                        </Setter.Value>
                                    </Setter>
                                </Style>
                            </sdk:DataGridTemplateColumn.HeaderStyle>
                            <sdk:DataGridTemplateColumn.CellTemplate>
                                <DataTemplate >
                                    <CheckBox HorizontalAlignment="Center" Margin="3" ></CheckBox>
                                </DataTemplate>
                            </sdk:DataGridTemplateColumn.CellTemplate>
                        </sdk:DataGridTemplateColumn>

 private void Chk_Checked(object sender, RoutedEventArgs e)
        {
            if (Datagrid1.ItemsSource != null)
            {
                foreach (DataGridRow dr in tsr.GetDataGridRows(Datagrid1))
                {
                    ((CheckBox)((DataGridCell)tsr.GetDataGridCell(Datagrid1, dr, 0)).Content).IsChecked = true;
                }
            }

        }

 private void Chk_Unchecked(object sender, RoutedEventArgs e)
        {
            if (Datagrid1.ItemsSource != null)
            {
                foreach (DataGridRow dr in tsr.GetDataGridRows(Datagrid1))
                {
                    ((CheckBox)((DataGridCell)tsr.GetDataGridCell(Datagrid1, dr, 0)).Content).IsChecked = false;
                }
            }
        }