When designing web maps (and for that matter, paper maps) we often try to take into account viewers who are color-blind. It would be helpful if you could preview in color-blind mode or design in color-blind mode so that you could have an idea of how your map/web map will look to someone who is color blind vs not color blind. I am suggesting a toggle mode. I overheard this idea during the UC. I'm surprised that it isn't already logged.