gistfile1.cs

<UserControl x:Class="UsercontrolContentControl.Overlay"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Width="400" Height="300">
    <Grid x:Name="LayoutRoot" Background="White">
        <ContentControl Content="{Binding OverlayContent}" />
    </Grid>
</UserControl>


    [ContentProperty("OverlayContent")]
    public partial class Overlay
    {
        public object OverlayContent
        {
            get { return GetValue(OverlayContentProperty); }
            set { SetValue(OverlayContentProperty, value); }
        }

        public static readonly DependencyProperty OverlayContentProperty =
            DependencyProperty.Register("OverlayContent",
                                        typeof(object),
                                        typeof(Overlay),
                                        new PropertyMetadata("", OnOverlayContentChanged));

        private static void OnOverlayContentChanged(object sender, DependencyPropertyChangedEventArgs args)
        {           
        }


        public Overlay()
        {
            InitializeComponent();
        }
    }

    <Grid x:Name="LayoutRoot">
        <local:Overlay>
            <local:MovieInfo />
        </local:Overlay>
    </Grid>