如何设置工具箱样式:wp8中的ListPicker全模式

我有问题的样式列表选择器的完整模式。我想让它完全覆盖整个页面，但是在full模式下我看到了从左到上的空白。

<toolkit:ListPicker Header="SELECT TRANSLATION" x:Name="lspTranslationLang"
SelectedItem="{Binding Name, Mode=TwoWay}" SelectionChanged="lspTranslationLang_SelectionChanged">
<toolkit:ListPicker.HeaderTemplate>
  <DataTemplate>
   <StackPanel>
     <TextBlock FontWeight="Bold" Foreground="Black" Text="Select Translation"></TextBlock>
   </StackPanel>
  </DataTemplate>
  </toolkit:ListPicker.HeaderTemplate>
  <toolkit:ListPicker.ItemTemplate>
  <DataTemplate>
   <StackPanel>
    <TextBlock FontSize="30" Text="{Binding Language}" />
   </StackPanel>
  </DataTemplate>
  </toolkit:ListPicker.ItemTemplate>
  <toolkit:ListPicker.FullModeItemTemplate>
  <DataTemplate>
    Grid Margin="0">
    <Grid.RowDefinitions>
      <RowDefinition Height="Auto"></RowDefinition>
      <RowDefinition Height="*"></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="Auto"></ColumnDefinition>
      <ColumnDefinition Width="*"></ColumnDefinition>
    </Grid.ColumnDefinitions>
    <Image Grid.Row="0" Margin="10,0,0,0" Width="30" Height="30" Grid.Column="0" Source="{Binding ImagePath}" ></Image>
    <TextBlock Grid.Row="0" Padding="10,0,10,0" Grid.Column="1" Text="{Binding Language}" FontSize="30"/>
    <TextBlock Grid.Row="1" Padding="10,0,10,0" Grid.Column="1" Text="{Binding Description}" FontSize="30"/>
    <Line X1="0" X2="480" Y1="0" Y2="0" Grid.Row="1" Grid.ColumnSpan="2" VerticalAlignment="Bottom" StrokeThickness="1" Stroke="LightGray" />
  </Grid>
  </DataTemplate>
  </toolkit:ListPicker.FullModeItemTemplate>
</toolkit:ListPicker>

如何更改列表选择器的完整模式的样式?