title: Why the property is not called on Binding in WPF?
body: <p>I am not sure why the property is not being called on Binding. Here is the code: </p>
  
  <pre><code>&lt;myusercontrol
  Text ="{Binding Description, UpdateSourceTrigger=LostFocus,Mode=TwoWay, ValidatesOnDataErrors=True}" 
   IsReadOnly ="{Binding AllowEditing}"
  /&gt;
  </code></pre>
  
  <p>And here is the myusercontrol IsReadOnly property: </p>
  
  <pre><code> public static DependencyProperty IsReadOnlyProperty = DependencyProperty.Register("IsReadOnly", typeof (bool),
                                                                                            typeof (
                                                                                                myusercontrol));
  
  
          public bool IsReadOnly
          {
              get
              {
                  return ((bool) GetValue(IsReadOnlyProperty));
              }
  
              set
              {
                  MessageBox.Show(value.ToString()); 
                  SetValue(IsReadOnlyProperty, !value); 
                  OnPropertyChanged("IsReadOnly");
              }
          }
  </code></pre>
  
  <p>The message box is never displayed! Any ideas!</p>