public void undo_frame(){
		if(!undo_frames.empty()){
			Frame tem = undo_frames.pop();
			current.suspendNotifications();
			for(int i = 0; i < current.getWidth(); i++){
				for(int j = 0; j < current.getHeight(); j++){
					current.setPixel(i, j, tem.getPixel(i, j));
				}
			}
			current.resumeNotifications();
		}
		
		
	}