event.clientY, last_pointer_client_pos['y'], 'clientY')
                            assert_equals(event.screenX, last_pointer_screen_pos['x'], 'screenX')
                            assert_equals(event.screenY, last_pointer_screen_pos['y'], 'screenY')
                        });
                    } else {
                        last_pointer_client_pos = {'x': event.clientX, 'y': event.clientY}
                        last_pointer_screen_pos = {'x': event.screenX, 'y': event.screenY}
                    }