MOUSE_PARAM_MAX
if (m->b + MOUSE_PARAM_BTN_OFF > MOUSE_PARAM_MAX)
if (x + MOUSE_PARAM_POS_OFF > MOUSE_PARAM_MAX)
buf[len++] = MOUSE_PARAM_MAX;
if (y + MOUSE_PARAM_POS_OFF > MOUSE_PARAM_MAX)
buf[len++] = MOUSE_PARAM_MAX;