[
  ClassInterface(ClassInterfaceType.AutoDispatch),
  DefaultBindingProperty("Rtf"),
  Description("DescriptionRichTextBox"),
  ComVisible(true), Docking(DockingBehavior.Ask),
  Designer("System.Windows.Forms.Design.RichTextBoxDesigner, System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")
]
public class RichTextBoxX : RichTextBox, INotifyPropertyChanged
{
  [
    Bindable(true),
    RefreshProperties(RefreshProperties.All),
    SettingsBindable(true),
    DefaultValue(false),
    Category("Appearance")
  ]
  new public string Rtf
  {
    get
    {
      return base.Rtf;
    }
    set
    {
      base.Rtf = value;
      RaisePropertyChanged("Rtf");
    }
  }

  protected override void OnTextChanged(System.EventArgs e)
  {
    base.OnTextChanged(e);
    RaisePropertyChanged("Rtf");
  }

  protected virtual void RaisePropertyChanged(string propertyName)
  {
    var pc = Interlocked.CompareExchange(ref PropertyChanged, null, null);
    if (pc!=null)
      pc(this, new PropertyChangedEventArgs(propertyName));
  }

  public event PropertyChangedEventHandler PropertyChanged;
}