That can happen with buttons too..

I had a gig few months ago, where I wanted to change the master EQ in my PSR2000 while the song was being played.

Rather than pressing the mixer setting button, I pressed the Demo button, they right next to eachother... and you can guess what happened.

I think the Demo button should be all the way on right or left as separate function.

touch screen is good for studio work, but for Live it is not so good, if there are NO physical buttons or knobs. look at the Roland VSynth for excellent use of touch screen and physical controls.

Also, the KORG i30 was pretty good too...