I was adjusting the loudness today using the steering wheel control and decided to change the station. No go. I later experimented using the radio knob, the steering wheel controls, and the video screen. I couldn't change the station while adjusting the loudness using any combination. Not that I would want to do that frequently, but I found it a curious piece of information.
At least for the switches on the steering wheel, several functions are shared per wire. So it can't detect multiple button press operations for related functions. The car distinguishes which button is pressed on each shared wire based on the resistance each switch presents to ground when pressed, but when 2 or more buttons are pressed, only the one with the lowest resistance (usually 0) "wins".
