title: styling the datatemplate to fit silverlight datgrid column header
body: <p>i have a style with datatemplate in xaml page as shown below . </p>
  
  <pre><code>&lt;
  
      Style x:Name="mytemplate" x:Key="mytemplate"  xmlns:dataprimitives="clr-namespace:System.Windows.Controls.Primitives;assembly=System.Windows.Controls.Data"
                                  TargetType="dataprimitives:DataGridColumnHeader"&gt;
                  &lt;Setter Property="ContentTemplate" &gt;
                      &lt;Setter.Value&gt;
                          &lt;DataTemplate&gt;
                              &lt;StackPanel Background="Aqua" Height="{Binding this.DataGridColumnHeader.Height}" Width="{Binding this.DataGridColumnHeaderWidth}" &gt;
         &lt;TextBlock Text="{Binding}"   HorizontalAlignment="Center" FontWeight="Black" &gt;&lt;/TextBlock&gt;
                                   &lt;TextBox x:Name="{Binding}" Padding="0,-1,0,0"  HorizontalAlignment="Stretch" Width="100" Height="20" KeyDown="txtfilterBox_KeyDown" LostFocus="txtfilterBox_LostFocus" /&gt;
                              &lt;/StackPanel&gt;
                          &lt;/DataTemplate&gt;
                      &lt;/Setter.Value&gt;
                  &lt;/Setter&gt;
              &lt;/Style&gt;
  </code></pre>
  
  <p>this style would be applied to the silverlight datgrid column header style.
  now i want the stackpanel inside the template to be same as the height and width of the 
  silverlight datgrid column header ? so how can that be done?</p>
  
  <p>else how to stretch the content template to fill the whole space of the datagrid column header</p>