/// <summary>
    ///   <para>Text label's color.</para>
    /// </summary>
    /// <param name="widget">Widget to call method on.</param>
    /// <param name="color">Label's color.</param>
    /// <returns>Reference to provided <paramref name="widget"/>.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="widget"/> is a <c>null</c> reference.</exception>
    /// <seealso cref="ISurfingbirdSurfButtonWidget.Color(string)"/>
    public static ISurfingbirdSurfButtonWidget Color(this ISurfingbirdSurfButtonWidget widget, SurfingbirdSurfButtonColor color)
    {
      Assertion.NotNull(widget);

      return widget.Color(color.ToString().ToLowerInvariant());
    }
        /// <summary>
        ///   <para>Text label's color.</para>
        /// </summary>
        /// <param name="widget">Widget to call method on.</param>
        /// <param name="color">Label's color.</param>
        /// <returns>Reference to provided <paramref name="widget"/>.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="widget"/> is a <c>null</c> reference.</exception>
        /// <seealso cref="ISurfingbirdSurfButtonWidget.Color(string)"/>
        public static ISurfingbirdSurfButtonWidget Color(this ISurfingbirdSurfButtonWidget widget, SurfingbirdSurfButtonColor color)
        {
            Assertion.NotNull(widget);

            return(widget.Color(color.ToString().ToLowerInvariant()));
        }