Silverlight and WPF have many similarities, and many differences as well. One of the subtle ones I’ve discovered is with respecting the HorizontalContentAlignment property in a ListBox. Here’s the same application, written in WPF and Silverlight with the following ListBox (bound to a collection of Book objects) and its item template:

   <ListBox HorizontalContentAlignment="Stretch" x:Name="_list">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <Border BorderBrush="Red" BorderThickness="2">
                    <Grid>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto" />
                        </Grid.RowDefinitions>
                        <TextBlock Text="{Binding BookName}" FontSize="20" />
                        <TextBlock Grid.Row="1" Text="{Binding Author}" FontSize="16" Foreground="Blue" />
                    </Grid>
                </Border>
            </DataTemplate>
        </ListBox.ItemTemplate>
    </ListBox>

The results are:

WPF:

Silverlight:

Not quite the same.

For some reason, Silverlight’s ListBox template does not carry the HorizontalContentAlignment to the inner ListBoxItem objects.

Fortunately, the solution is simple: add an ItemContainerStyle property to the ListBox and set the HorizontalContentAlgnment to “Stretch”:

<ListBox.ItemContainerStyle>
  <Style TargetType="ListBoxItem">
    <Setter Property="HorizontalContentAlignment" Value="Stretch" />
  </Style>
</ListBox.ItemContainerStyle>

The result: