Quote Originally Posted by Kamikaze47 View Post
I assume the switches are right next to eachother? if so, why not make it so that mode 4 can be activated by pressing 2 and 3 at the same time. To do this i would suggest that for the interrupt handler for switch 3, have a quick loop that checks button 2 for a short time (something like 20ms). If it is pressed, activate mode 4, else activate mode 3.

The "double click" can be done too, but requires a bit more logic and probably a timer.
Thanks for your input...I'd pondered that option - and yes the switches are near each other - but I worry a little over the actual logistics. A guitarist will be selecting these switches with his right hand - this will already have a plectrum in it (between the thumb and forefinger), this leave him needing to press two switches concurrently but with two fingers partially out of action - then there's the accuracy at landing fingers on two small (3.5mm diameter) button tops 'on the fly' in mid solo etc on a dimly lit stage etc.