/// <summary>
        ///
        /// </summary>
        /// <param name="button"></param>
        public void UpdateButton(SipButton button)
        {
            if (button == null)
            {
                throw new ArgumentNullException("button");
            }

            using (var g = CreateGraphics())
            {
                button.Draw(g, (selectedButton == button) && isInside);
            }
        }