I'm quite new to WPF and I'm sure I'm missing something trivial. The scrollviewer does not work when the content of the stackpanel grows.
<ItemsControl>
                <TextBlock Margin="30,4,0,4" Text="Associated Data: None" Visibility="{Binding SelectedPBL.PBLData.Count, Converter={StaticResource VisibleIfZero}}"/>
                <ScrollViewer>
                    <StackPanel Margin="30,4,0,4" Orientation="Horizontal" Visibility="{Binding SelectedPBL, Converter={StaticResource CollapsedIfNull}}" ScrollViewer.VerticalScrollBarVisibility="Auto">
                        <TextBlock FontSize="12" Text="Associated Data:" Visibility="{Binding SelectedPBL.PBLData.Count, Converter={StaticResource CollapsedIfZero}}"/>
                        <ItemsControl FontSize="12" ItemsSource="{Binding SelectedPBL.PBLData}" >
                            <ItemsControl.ItemTemplate>
                                <DataTemplate>
                                    <WrapPanel Margin="20,0,20,0" Orientation="Horizontal">
                                        <TextBlock Margin="0,0,10,0" Text="{Binding Path=Key, StringFormat=({0})}"/>
                                        <TextBlock Text="{Binding Path=Value}"/>
                                    </WrapPanel>
                                </DataTemplate>
                            </ItemsControl.ItemTemplate>
                        </ItemsControl>
                </StackPanel>
                </ScrollViewer>
            </ItemsControl>
 
    