Move down overflow contents in horizontal stackpanel

Question

I have a list box in expander:

<ListBox ItemsSource="{Binding MySource">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <RadioButton Content="{Binding MyContent}" />
        </DataTemplate>
    </ListBox.ItemTemplate>
    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <StackPanel Orientation="Horizontal" />
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>
</ListBox>

I wrap the radio button with horizontal orientation stackpanel. I want the overflow radio buttons move down like right image shown below (no horizontal scrollbar). Now, mine is like the left one.

Answer 1

You need to use a WrapPanel, not a StackPanel. In WPF it's built into the main assemblies but in Silverlight you'll need to get the Silverlight Toolkit.

<ListBox ScrollViewer.HorizontalScrollBarVisibility="Disabled" ItemsSource="{Binding MySource">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <RadioButton Content="{Binding MyContent}" />
        </DataTemplate>
    </ListBox.ItemTemplate>
    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <t:WrapPanel />
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>
</ListBox>