message: Fix panic when closing window
  Resolves
diff: @@ -129,8 +129,8 @@ impl<N: Notify> Processor<N> {
  .expect("write size.json");
  }
  - // FIXME
  - panic!("window closed");
  + // FIXME should do a more graceful shutdown
  + ::std::process::exit(0);
  },
  glutin::Event::Resized(w, h) => {
  resize_tx.send((w, h)).expect("send new size");
  