User Controls, Dependency Properties, TwoWay Binding, and Hair Pulling!

1

Hi,

I have this user control…

<UserControl x:Class=“SilverlightApplication.UserControls.FormItem_TextBox”
xmlns=“http://schemas.microsoft.com/winfx/2006/xaml/presentation”
xmlns:x=“http://schemas.microsoft.com/winfx/2006/xaml”
>

&lt;StackPanel Orientation="Vertical" &gt;

    &lt;TextBlock x:Name="lbCaption" Style="{StaticResource TextBlockStyle}" /&gt;
    &lt;TextBox x:Name="tbItem"  Style="{StaticResource TextBoxStyle}" /&gt;

&lt;/StackPanel&gt;

</UserControl>

…which has this code behind…

public partial class FormItem_TextBox : UserControl
{

    public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(String), typeof(FormItem_TextBox), new PropertyMetadata(TextChanged));
    public static readonly DependencyProperty CaptionProperty = DependencyProperty.Register("Caption", typeof(String), typeof(FormItem_TextBox), new PropertyMetadata(CaptionChanged));

    public String Text
    {
        get { return (String)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    public String Caption
    {
        get { return (String)GetValue(CaptionProperty); }
        set { SetValue(CaptionProperty, value); }
    }

    private static void TextChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
    {
        FormItem_TextBox item = (source as FormItem_TextBox);        
        item.tbItem.Text = e.NewValue.ToString();            
    }

    private static void CaptionChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
    {    
        FormItem_TextBox item = (source as FormItem_TextBox);
        item.lbCaption.Text = e.NewValue.ToString();
    }

    public FormItem_TextBox()
    {
        InitializeComponent();
    }

}

How comes that when I attempt to TwoWay databind to the controls TextProperty, like so…

<UC:FormItem_TextBox Caption=“First Name: " Text=”{Binding Path=FirstName, Mode=TwoWay}" />

…it doesn’t play ball??

I know my MVVM stuff is OK because I have tested it on a simple text box, i.e.

<TextBox Text="{Binding Path=FirstName, Mode=TwoWay}" />

…and it works just fine.

Is there any other wiring up that is needed within my user control??

I am brand spanking new to silverlight/WPF, so please be gentle!!!

Many thanks for any responses.

ETFairfax