evSubTime
idle = evSubTime(ctx->lastEventTime, this->lastTouched);
this->timer->inter = evSubTime(this->max_idle, idle);
interval = evSubTime(ctx->lastEventTime,
t = evSubTime(nextTime, ctx->lastEventTime);
interval = evSubTime(evNowTime(), start_time);
timeout = evSubTime(finish, now);
timeout = evSubTime(finish, now);
struct timespec evSubTime __P((struct timespec, struct timespec));