Eu tenho esse XAML para um UserControl:

<UserControl x:Class="SW.Resources.Controls.HistoryProgressBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
d:DesignHeight="480" d:DesignWidth="480">

<Grid x:Name="LayoutRoot" Style="{StaticResource AppBackgroundStyle}">
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="223" />
        <ColumnDefinition Width="223" />
        <ColumnDefinition Width="10" />
    </Grid.ColumnDefinitions>

    <TextBlock x:Name="TitleText" Style="{StaticResource TitleListItemStyle}" Text="41xxfd" TextWrapping="Wrap" Grid.ColumnSpan="2"/>
    <TextBlock x:Name="leftValue"  HorizontalAlignment="Right" Style="{StaticResource DetailListItemStyle}" Text="Category: " Grid.Row="1" Grid.Column="0"/>
    <TextBlock x:Name="rightValue" Style="{StaticResource DetailListItemValueStyle}" Text="tv" Grid.Row="1" Grid.Column="1" />
    <TextBlock x:Name="subLeftValue" HorizontalAlignment="Right" Style="{StaticResource DetailListItemStyle}" Text="Size: " Grid.Row="2" Grid.Column="0" />
    <TextBlock x:Name="subRightValue" Style="{StaticResource DetailListItemValueStyle}" Text="400MB" Grid.Row="2" Grid.Column="1"  />
    <Rectangle Fill="Red" x:Name="progressColor" Grid.RowSpan="4" Grid.Column="2"/>
</Grid>

Parece exatamente como eu quero no Portrait. Mas na paisagem, o controle termina cedo. Idealmente, eu teria esse controle estendido para cobrir a tela inteira. Isso é possível sem a necessidade de código extra para mudar para o modo Paisagem?