title: How to catch a property changed event after binding
body: <p>I have a custom <code>UserControl</code>:</p>
  
  <pre><code>public partial class CustomCtrl : UserControl
  {
      public CustomCtrl()
      {
          InitializeComponent();
      }
  
      public string Prova
      {
          get { return (string)GetValue(ProvaProperty); }
          set 
          {
              SetValue(ProvaProperty, value); 
          }
      }
  
      public static readonly DependencyProperty ProvaProperty =
          DependencyProperty.Register("Prova", typeof(string), typeof(CustomCtrl));
  
  }
  </code></pre>
  
  <p>I do this simple binding:</p>
  
  <pre><code>CustomCtrl c = new CustomCtrl();
  TextBlock t = new TextBlock();
  c.SetBinding(CustomCtrl.ProvaProperty, new Binding("Text") { Source = t });
  t.Text = "new string";
  </code></pre>
  
  <p>Now <code>c.Prova</code> is "<code>new string</code>", but how can I catch in my <code>CustomControl</code> class the event informing me that <code>Prova</code> has changed?</p>