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 the 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 (!).

Why 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>

Bahr

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.

Kreager

In my case I had put the ListBox inside a ScrollViewer too and the ListBoxItems were stretching as wide as they wanted outside the size of the ListBox. Removing the ScrollViewer and setting ScrollViewer.VerticalScrollBarVisibility="Visible" and ScrollViewer.HorizontalScrollBarVisibility="Disabled" did the trick. Thank you for your help! – Lagting

Answer 2

ListBox already contains ScrollViewer. By default the ScrollBar will show up when there is more content than space. But some containers resize themselves to accommodate their contents (e.g. StackPanel), so there is never "more content than space". In such cases, the ListBox is always given as much space as is needed for the content.

In order to calculate the condition of having more content than space, the size should be known. Make sure your ListBox has a constrained size, either by setting the size explicitly on the ListBox element itself, or from the host panel.

In case the host panel is vertical StackPanel and you want VerticalScrollBar you must set the Height on ListBox itself. For other types of containers, e.g. Grid, the ListBox can be constrained by the container. For example, you can change your original code to look like this:

<Grid Name="grid1">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="2*"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
        </Grid.RowDefinitions>
        <ListBox Grid.Row="0" Name="lstFonts" Margin="3"
                 ItemsSource="{x:Static Fonts.SystemFontFamilies}"/>
    </Grid>
</Grid>

Note that it is not just the immediate container that is important. In your example, the immediate container is a Grid, but because that Grid is contained by a StackPanel, the outer StackPanel is expanded to accommodate its immediate child Grid, such that that child can expand to accommodate its child (the ListBox).

If you constrain the height at any point — by setting the height of the ListBox, by setting the height of the inner Grid, or simply by making the outer container a Grid — then a vertical scroll bar will appear automatically any time there are too many list items to fit in the control.

Escapement

Using a DockPanel as parent container omits the need of knowing how many elements you plan to add as child or predefine any Height Attribute. For each child define DockPanel.Dock=Top. This make your "Scrollviewer-Childs" showing their Scrollbars as needed. Not tested generally, it did work in my usecase. BR, Daniel – Coxcomb

TLDR: Change your parent element from StackPanel to Grid since StackPanel always expands to the height of its children. – Inimitable

Answer 3

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

Bahr

Try to avoid using the height and width properties as they can make changes down the road difficult. You're better off going with JaredPar's solution. – Toxicosis

I do that but it just puts a "scrollbar area" to the right with no scrollbar itself, and my list goes down past the bottom of my window down to all eternity, how can I tell the listbox (stop at the bottom of the window)? – Bahr

Because it's in a StackPanel, it's merrily being given all the space it needs, so it doesn't think it needs a scrollbar. – Thereafter

This worked for me ( I've just set MinHeight and MaxHeight instead of fixed Height). Thanks. – Cispadane

Answer 4

Scroll Bar is added to the List box automatically unless its visibility is set to Hidden. Whenever the size of List Items exceeds the one, which can be shown inside a list box vertical or horizontal list box can be seen during the run time.

Crankcase

Answer 5

In my case the number of items in the ListBox is dynamic so I didn't want to use the Height property. I used MaxHeight instead and it works nicely. The scrollbar appears when it fills the space I've allocated for it.

Eliciaelicit

Answer 6

I was having the same problem, I had a ComboBox followed by a ListBox in a StackPanel and the scroll bar for the ListBox was not showing up. I solved this by putting the two in a DockPanel instead. I set the ComboBox DockPanel.Dock="Top" and let the ListBox fill the remaining space.

Oliveira

Answer 7

XAML ListBox Scroller - Windows 10(UWP)

<Style TargetType="ListBox">
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Visible"/>
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Visible"/>
</Style>

Partlow