uttons,
            "pageX": event.pageX,
            "pageY": event.pageY,
            "ctrlKey": event.ctrlKey,
            "metaKey": event.metaKey,
            "altKey": event.altKey,
            "shiftKey": event.shiftKey,
            "target": event.target.id
          });
          appendMessage(event.type + " " +
              "button: " + event.button + ", " +
              "pageX: " + event.pageX + ", " +
              "pageY: " + event.pageY + ", " +
              "button: " + event.button + ", "