public string TitleUrl
{
  get
  {
    object objTitle = ViewState["TitleUrl"];
    if (objTitle == null)
      return String.Empty;

    return (string)objTitle;
  }
  set
  {
    ViewState["TitleUrl"] = value;
  }
}

// Update the selected IWebPart property value.
void Button1_Click(object sender, EventArgs e)
{
  String propertyValue = Server.HtmlEncode(TextBox3.Text);
  TextBox3.Text = String.Empty;

  switch (RadioButtonList1.SelectedValue)
  {
    case "title":
      this.Title = propertyValue;
      break;
    case "description":
      this.Description = propertyValue;
      break;
    case "catalogiconimageurl":
      this.CatalogIconImageUrl = propertyValue;
      break;
    case "titleiconimageurl":
      this.TitleIconImageUrl = propertyValue;
      break;
    case "titleurl":
      this.TitleUrl = propertyValue;
      break;
    default:
      break;
  }
}