WPF zegar Conrt

<DataGrid AutoGenerateColumns="False" ItemsSource="{Binding TestList}">
            <DataGrid.Columns>
            <DataGridTemplateColumn Header="Start">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding Start, StringFormat=d}" FontFamily="Verdana" />
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
            <DataGridTemplateColumn.CellEditingTemplate>
                <DataTemplate>
                    <DatePicker SelectedDate="{Binding Start}" FontFamily="Verdana"  >
                        <DatePicker.CalendarStyle>
                            <Style TargetType="Calendar">
                                <Setter Property="DisplayMode" Value="Month"/>
                            </Style>
                        </DatePicker.CalendarStyle>
                    </DatePicker>
                </DataTemplate>
            </DataGridTemplateColumn.CellEditingTemplate>
        </DataGridTemplateColumn>
            </DataGrid.Columns>
        </DataGrid>
Upset Unicorn