last = e.screenX;
                    screenY_last = e.screenY;

                    updateData();
                }
            }
        });

        function updateData() {
            screenX_init_log.innerHTML = screenX_init;
            screenY_init_log.innerHTML = screenY_init;
            screenX_last_log.innerHTML = screenX_last;
            screenY_last_log.innerHTML = screenY_last;
            screenX_delta_log.innerHTML = screenX_delta;
            screenY_delta_log.innerHTML = screenY_delta;
  