virtual int next_frame(Time& time)
	{
		if(!alive_flag)
			return 0;
		return warm_target->next_frame(time);

	}
	virtual int next_frame(Time& time)
	{
		Glib::Mutex::Lock lock(mutex);
		if(!alive_flag)
			return 0;
		return warm_target->next_frame(time);
		
	}