C#: Make a .NET form control flash.

        /// <summary>

        /// Flashes the control.

        /// </summary>

        /// <param name="control"></param>

        /// <param name="spanOff"></param>

        public static void Blink( [CanBeNull] this Control control, [CanBeNull] TimeSpan? spanOff = null ) {

            if ( null == control ) {

                return;

            }

            if ( !spanOff.HasValue ) {

                spanOff = 333;

            }

            control.OnThread( () => {

                var foreColor = control.ForeColor;

                control.ForeColor = control.BackColor;

                control.BackColor = foreColor;

                control.Refresh();

            } );

            var timer = new Timer { AutoReset = false, Interval = spanOff.Value.TotalMilliseconds };

            timer.Elapsed += ( sender, args ) => {

                control.OnThread( () => {

                    control.ResetForeColor();

                    control.ResetBackColor();

                    control.Refresh();

                } );

                using ( timer ) { timer = null; }

            };

            GC.KeepAlive( timer );

            timer.Start();

        }