R – ControlSets and CurrentControlSets

The answer is to not use a UserControl to do it.

Create a class that extends ContentControl

public class MyFunkyControl : ContentControl
{
    public static readonly DependencyProperty HeadingProperty =
        DependencyProperty.Register("Heading", typeof(string),
        typeof(MyFunkyControl), new PropertyMetadata(HeadingChanged));

    private static void HeadingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        ((MyFunkyControl) d).Heading = e.NewValue as string;
    }

    public string Heading { get; set; }
}

then use a style to specify the contents

<Style TargetType="control:MyFunkyControl">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="control:MyFunkyControl">
                <Grid>
                    <ContentControl Content="{TemplateBinding Content}"/>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

and finally - use it

<control:MyFunkyControl Heading="Some heading!">            
    <Label Name="WithAName">Some cool content</Label>
</control:MyFunkyControl>

The main difference between User Control, Custom Control and Component is that they inherit from different levels in the inheritance tree:

MyComponent
   |-> Component

MyCustomControl
   |-> Control
          |-> Component

MyUserControl
   |-> ContainerControl
          |-> ScrollableControl
                 |-> Control
                        |-> Component

So, in short you get a different amount of pre-wired functionality with the different options.

When would you use the different options? (these are thoughts and opinions, not truths)

• Create a component if you want to provide functionality without UI (such as Timer components, data sources, ...)
• Create a custom control if you want to make a component where you have full control over its visual appearance, and you don't want any baggage of unnecessary functionality. Typical cases would be simple controls with limited functionality (such as a button)
• Create a user control if you are going to combine existing controls into reusable building blocks (such as two lists with buttons where you can move items between the lists).