title: DatePicker is OneWay, but I need TwoWay
body: <p>I have following DataGrid in wpf.</p>
  
  <pre><code>&lt;DataGrid AutoGenerateColumns="False" Grid.Row="1" Name="adsGrid" ItemsSource="{Binding Path=Ads}" CanUserAddRows="False" CanUserDeleteRows="False" SelectionChanged="adsGrid_SelectionChanged"&gt;
              &lt;DataGrid.Columns&gt;
                  &lt;DataGridTextColumn Header="ID" Binding="{Binding Path=ID}" IsReadOnly="True" /&gt;
                  &lt;DataGridTextColumn Header="File" Binding="{Binding Path=FileName}" IsReadOnly="True" /&gt;                
                  &lt;DataGridTemplateColumn Header="Expiration date" IsReadOnly="True"&gt;
                      &lt;DataGridTemplateColumn.CellTemplate&gt;
                          &lt;DataTemplate&gt;
                              &lt;DatePicker SelectedDate="{Binding Path=ExpirationDate}" /&gt;
                          &lt;/DataTemplate&gt;
                      &lt;/DataGridTemplateColumn.CellTemplate&gt;
                  &lt;/DataGridTemplateColumn&gt;
                  &lt;DataGridTextColumn Header="Info" Width="100*" Binding="{Binding Path=Info}" /&gt;
              &lt;/DataGrid.Columns&gt;
          &lt;/DataGrid&gt;
  </code></pre>
  
  <p>Problem is that DateTime picker won't update related object but will read value from it. I've tried adding Mode=TwoWay but it didn't help. Other properties are updated properly.</p>