Many years ago we went to hear Yehudi Menuhin playing Beethoven's violin concerto at the Albert Hall. Our dear friend Harry, much older than us, and pretty deaf by then, was sitting across the aisle from us, so we couldn't communicate with him during the performance. He spent the whole performance with his hand in his jacket pocket, jangling his bunch of keys. :-)

Don't be too quick to be sniffy about people who clap between movements. In Mozart's and Beethoven's time, such enthusiastic outbursts (not only between movements but also in the middle of 'em) were de rigeur at concerts, not just expected but much-appreciated by performers. Even chattering during performances was quite normal and not usually frowned on. Indignant tutting disapproval of even quite mild applause between movements is a modern affectation (a bit like wearing ties, which I've refused to do for decades).

We can stay at home these days and listen to gorgeous recordings of whole symphonies on our super-duper speakers, undistracted by audience participation. I suspect that being able to do that has helped to condition us to expect the same at concerts. I think that's a big mistake!