在Windows Phone 8.1上扩展而不是滚动问题

Question

我试图达到以下效果：可滚动（垂直）的项目列表;如果有这样的需要，每个项目应该可以水平滚动。我尝试了以下代码：

        <ScrollViewer x:Name="historyViewer" 
                      VerticalScrollMode="Enabled" VerticalScrollBarVisibility="Hidden"
                      HorizontalScrollMode="Disabled" HorizontalScrollBarVisibility="Hidden">
            <ItemsControl ItemsSource="{Binding History}">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Vertical" HorizontalAlignment="Stretch">
                            <ScrollViewer VerticalScrollMode="Disabled" VerticalScrollBarVisibility="Hidden"
                                          HorizontalScrollMode="Enabled" HorizontalScrollBarVisibility="Hidden">
                                <TextBlock Foreground="{ThemeResource PhoneMidBrush}" FontSize="{ThemeResource TextStyleExtraLargeFontSize}" HorizontalAlignment="Left" Text="{Binding Expression}" />
                            </ScrollViewer>
                            <ScrollViewer x:Name="resultScroll" VerticalScrollMode="Disabled" VerticalScrollBarVisibility="Hidden"
                                          HorizontalScrollMode="Enabled" HorizontalScrollBarVisibility="Hidden">
                                <TextBlock FontSize="{ThemeResource TextStyleExtraLargePlusFontSize}" HorizontalAlignment="Right" Text="{Binding Result}" />
                            </ScrollViewer>
                        </StackPanel>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </ScrollViewer>

问题是，如果列表项太宽，它们会扩展主滚动查看器的宽度而不是可滚动 - 即使它的水平对齐设置为拉伸。

我该如何解决？