How can I get a vertical scrollbar in my ListBox?

Question

In the example below I have a ListBox with dozens of font names in it.

I would have thought it would automatically have a vertical scrollbar on it so that you can select ANY font, not just the first ones in teh list, but it doesn't.

So I added a "ScrollViewer" and that puts a "scrollbar area" on the right but there is no scrollbar in the scrollbar area so that you can scroll (!).

What isn't a scrollbar automatic and how do I force it to have a scrollbar?

    <StackPanel Name="stack1">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="*"></RowDefinition>
            </Grid.RowDefinitions>
            <ScrollViewer>
                <ListBox Grid.Row="0" Name="lstFonts" Margin="3"  ItemsSource="{x:Static Fonts.SystemFontFamilies}"/>
            </ScrollViewer>
        </Grid>
    </StackPanel>

Answer 1

The problem with your solution is you're putting a scrollbar around a ListBox where you probably want to put it inside the ListBox.

If you want to force a scrollbar in your ListBox, use the ScrollBar.VerticalScrollBarVisibility attached property.

<ListBox 
    ItemsSource="{Binding}" 
    ScrollViewer.VerticalScrollBarVisibility="Visible">
</ListBox>

Setting this value to Auto will popup the scrollbar on an as needed basis.

Answer 2

I added a "Height" to my ListBox and it added the scrollbar nicely.