Adding heading to existing control - wpf

Question

I want to create a custom control type that behaves exactly like a ListBox, except that it displays with a heading above it.
I think what I need to do is inherit from ListBox and use code like the following:
var originalTree = Template.VisualTree;
var panel = new FrameworkElementFactory(typeof(StackPanel));
var heading = new FrameworkElementFactory(typeof(TextBlock));
heading.SetValue(TextBlock.TextProperty, "Heading");
panel.AppendChild(heading);
panel.AppendChild(originalTree);
Template.VisualTree = panel;
Except wherever I tried to place it, it didn't work, because Template.VisualTree was null. What am I doing wrong?

Answer 1

As far as i know templates can be defined in various ways, if the VisualTree is null, it has been generated 'by reference', in that case it has been set with Frameworktemplate.Template.
(Editing that is not intended, all members are internal or private)
I would use a UserControl if you are going to take the whole root anyway.
Edit: Copying and editing the default template should be fine as well, here is the default style:
<SolidColorBrush x:Key="ListBorder" Color="#828790"/>
<Style TargetType="{x:Type ListBox}">
<Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
<Setter Property="BorderBrush" Value="{StaticResource ListBorder}"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="ScrollViewer.PanningMode" Value="Both"/>
<Setter Property="Stylus.IsFlicksEnabled" Value="False"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBox}">
<Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="1" SnapsToDevicePixels="true">
<ScrollViewer Focusable="false" Padding="{TemplateBinding Padding}">
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</ScrollViewer>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
(You could bind the header TextBox.Text to the ListBox.Tag then you do not need to subclass it)
Default templates and styles are on MSDN.

Answer 2

This article http://www.wpftutorial.net/CustomVsUserControl.html implies that a UserControl is a conglomerate of several controls - in your case a Label or TextBlock plus a ListBox? So is a user control a possible solution?