Problema oculto de la barra de desplazamiento XAML ScrollViewer (Silverlight)

Question

Tengo este extraño problema por el cual el contenido dentro de un visor de desplazamiento aumenta de tamaño, el visor de desplazamiento muestra la barra de desplazamiento horizontal. Sin embargo, la cuadrícula en la que se encuentra el ScrollViewer no parece redimensionarse lo suficiente como para mostrar la barra de desplazamiento.

He aislado el problema en esta aplicación de muestra, básicamente algo de xaml y algo de código para simular el aumento del tamaño del contenido.

Tenga en cuenta que la barra de desplazamiento derecha no se muestra correctamente cuando hace clic en el botón para cambiar el tamaño, agregué algo de relleno para mostrar que está allí pero no en el lugar correcto.

Si elimino la fila superior, parece funcionar.

¿Alguna idea y gracias de antemano chicos y chicas?

<UserControl x:Class="SilverlightApplication7.MainPage"
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"
>
<Grid 
    ShowGridLines="True" 
    HorizontalAlignment="Stretch" 
    VerticalAlignment="Stretch"
>
    <Grid.RowDefinitions>
        <RowDefinition x:Name="DealHeaderRow" Height="Auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition x:Name="DealBarColumn" Width="Auto"></ColumnDefinition>
        <ColumnDefinition x:Name="MarketViewerColumn" Width="Auto"></ColumnDefinition>
        <ColumnDefinition x:Name="DealEditorColumn" Width="*" ></ColumnDefinition>
        <ColumnDefinition x:Name="InfoColumn" Width="Auto"></ColumnDefinition>
    </Grid.ColumnDefinitions>

    <ContentControl 
        x:Name="DealBarRegionContentControl"
        Grid.Row="0"
        Grid.Column="0" 
        Grid.RowSpan="2"
        VerticalContentAlignment="Stretch"
        HorizontalAlignment="Stretch"
        Margin="0">
        <TextBlock Text="DealBarRegion" Width="150" />
    </ContentControl>

    <ContentControl 
        Grid.Row="0"
        Grid.Column="1" 
        Grid.RowSpan="2"
        VerticalContentAlignment="Stretch"
        HorizontalAlignment="Stretch"
        HorizontalContentAlignment="Stretch">
        <Border Background="#FF9AF172">
            <TextBlock Text="MarketViewerRegion"  Width="150"  />
        </Border>
    </ContentControl>

    <ContentControl 
        Grid.Column="2" 
        Grid.ColumnSpan="2"
        Grid.Row="0"
        HorizontalAlignment="Stretch"
        HorizontalContentAlignment="Stretch" >
        <Border Background="#FFC1FC9F">
            <TextBlock Text="DealHeaderRegion"  />
        </Border>
    </ContentControl>

    <ContentControl 
        Grid.Column="2" 
        Grid.Row="1" 
        VerticalAlignment="Top"
        HorizontalContentAlignment="Stretch" 
        VerticalContentAlignment="Stretch">
        <Border Background="MistyRose" >
            <TextBlock Text="DealEditorRegion" />
        </Border>
    </ContentControl>

    <Grid
        Grid.Column="3" 
        Grid.Row="1" 
    >
        <ContentControl 
            x:Name="InfoRegionControl" 
            VerticalContentAlignment="Stretch"
            HorizontalAlignment="Stretch">
            <!-- without the padding here you can't see the scroll bar at all !! Its like the 
            scroll ScrollViewer isn't correctly calculating its width to include the scroll bar,
            or the grid isn't sizing at the points its visible??-->
            <Border Padding="0,0,9,0" MinWidth="200" x:Name="DealInfoControlPlaceHolder">
                <ScrollViewer  
                    HorizontalAlignment="Stretch" 
                    HorizontalContentAlignment="Stretch"
                    VerticalScrollBarVisibility="Auto" 
                    HorizontalScrollBarVisibility="Auto"  
                    >
                    <StackPanel x:Name="ScrollContentPlaceHolder">
                        <Button Click="Button_Click" Content="Rezize Column" x:Name="ResizeButton" />
                    </StackPanel>
                </ScrollViewer>
            </Border>
        </ContentControl>
    </Grid>
</Grid>

Y aquí está el código detrás:

using System.Windows;
using System.Windows.Controls;

namespace SilverlightApplication7
{
    public partial class MainPage : UserControl
    {
        double _dealInfoControlPlaceHolderHeight = 0;
        double _dealInfoControlPlaceHolderWidth = 0;

        public MainPage()
        {
            InitializeComponent();

            Loaded += (o, e) =>
            {
                // cache the original width and height
                _dealInfoControlPlaceHolderHeight = DealInfoControlPlaceHolder.Height;
                _dealInfoControlPlaceHolderWidth = DealInfoControlPlaceHolder.Width;
            };
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            if (ScrollContentPlaceHolder.Height == 1200)
            {
                ScrollContentPlaceHolder.Height = _dealInfoControlPlaceHolderHeight;
                ScrollContentPlaceHolder.Width = _dealInfoControlPlaceHolderWidth;
            }
            else
            {
                ScrollContentPlaceHolder.Height = 1200;
                ScrollContentPlaceHolder.Width = 250;
            }
        }
    }
}

Answer 1

Ok, no sé por qué lo anterior no funciona, pero como solución alternativa solo reestructuro la página para que se comporte igual. Eso funciona:

<UserControl x:Class="SilverlightApplication7.MainPage"
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"
>
<Grid 
    ShowGridLines="True" 
    HorizontalAlignment="Stretch" 
    VerticalAlignment="Stretch"
>
    <Grid.RowDefinitions>
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition x:Name="DealBarColumn" Width="Auto"></ColumnDefinition>
        <ColumnDefinition x:Name="MarketViewerColumn" Width="Auto"></ColumnDefinition>
        <ColumnDefinition x:Name="DealEditorColumn" Width="*" ></ColumnDefinition>
    </Grid.ColumnDefinitions>

    <ContentControl 
        x:Name="DealBarRegionContentControl"
        Grid.Column="0" 
        VerticalContentAlignment="Stretch"
        HorizontalAlignment="Stretch"
        Margin="0">
        <TextBlock Text="DealBarRegion" Width="150" />
    </ContentControl>

    <ContentControl 
        Grid.Column="1" 
        VerticalContentAlignment="Stretch"
        HorizontalAlignment="Stretch"
        HorizontalContentAlignment="Stretch">
        <Border Background="#FF9AF172">
            <TextBlock Text="MarketViewerRegion"  Width="150"  />
        </Border>
    </ContentControl>

    <Grid
        Grid.Column="2" >
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

        <ContentControl 
            Grid.Row="0"
            HorizontalAlignment="Stretch"
            HorizontalContentAlignment="Stretch" >
            <Border Background="#FFC1FC9F">
                <TextBlock Text="DealHeaderRegion"  />
            </Border>
        </ContentControl>

        <Grid 
            Grid.Row="1"     
            HorizontalAlignment="Stretch"
            VerticalAlignment="Stretch"
            >
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"></ColumnDefinition>
                <ColumnDefinition Width="Auto"></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <ContentControl 
                Grid.Column="0"
                VerticalAlignment="Top"
                HorizontalContentAlignment="Stretch" 
                VerticalContentAlignment="Stretch">
                <Border Background="MistyRose" >
                    <TextBlock Text="DealEditorRegion" />
                </Border>
            </ContentControl>
            <ContentControl 
                Grid.Column="1"
                x:Name="InfoRegionControl" 
                VerticalContentAlignment="Stretch"
                HorizontalAlignment="Right">
                <!-- without the padding here you can't see the scroll bar at all !! Its like the 
                scroll ScrollViewer isn't correctly calculating its width to include the scroll bar,
                or the grid isn't sizing at the points its visible??-->
                <Border Padding="0,0,9,0" MinWidth="200" x:Name="DealInfoControlPlaceHolder">
                    <ScrollViewer  
                        HorizontalAlignment="Stretch" 
                        HorizontalContentAlignment="Stretch"
                        VerticalScrollBarVisibility="Auto" 
                        HorizontalScrollBarVisibility="Auto"  
                        >
                        <StackPanel x:Name="ScrollContentPlaceHolder">
                            <Button Click="Button_Click" Content="Rezize Column" x:Name="ResizeButton" />
                        </StackPanel>
                    </ScrollViewer>
                </Border>
            </ContentControl>
        </Grid>
    </Grid>
</Grid>