122 of 365: Strumming the violin - mandolin chords or roll my own?

I went to see John Etheridge and Chris Garrick perform "At the Dimming of the Day" at the Cambridge Jazz in Kettle's Yard a few weeks back. It was a fantastic evening. One of the things that struck me was that often, as John and Chris passed the melody between each other, Chris would accompany John not by bowing his violin, but by holding it guitar style and strumming it. He sounded great and I wondered how he did it. He was using amplification (he had two acoustic violins mic'ed up, and two electric ones). I wonder if he was using mandolin chords? The mandolin has the same tuning as the violin, but the violin strings are so close together its hard for the fingers placed on the lower strings not to overlap the higher ones. Oh well, I'll see what I can work out. It might be a fun way to do some improvisation work with my son Will on guitar.