WPF listbox WrapPanel Horizontal无效的原因

http://stackoverflow.com/questions/4244793/listbox-not-showing-items-horizontally-after-using-theme

           <ListBox.ItemsPanel>

                <ItemsPanelTemplate>

                    <WrapPane Orientation="Horizontal"l></WrapPanel>

                </ItemsPanelTemplate>

            </ListBox.ItemsPanel>

无法正常横向显示,原因应用了Theme,修改对应的Theml.xaml

<ControlTemplate TargetType="{x:Type ListBox}">
    <Grid>
        <Border x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2" Background="{DynamicResource ControlBackgroundBrush}" />
        <ScrollViewer Margin="1" Style="{DynamicResource NuclearScrollViewer}" Focusable="false" Background="{x:Null}">
            <StackPanel Margin="1,1,1,1" IsItemsHost="true" />
        </ScrollViewer>
    </Grid>

修改 StackPanel to an ItemsPresenter:

<ItemsPresenter Margin="1,1,1,1"/>