public void ctrl_y()
	{
		if(id_hist < actions.size()-1)
		{
			id_hist++;
			Action a = actions.get(id_hist);
			switch(a.getNum())
			{
			case 1:
				coord.add(a.getNode());
				break;
			case 2:
				delete(a.getNode());
				break;
			case 3:
				trace.add(a.getTrace());
				break;
			case 4:
				delTrace(a.getTrace());
				break;
			case 5:
				a.getNode().setStart(a.getNewStart());
				a.getNode().setEnd(a.getNewEnd());
				a.getNode().setName(a.getNewName());
				break;
			case 6:
				actions.get(id_hist).getTrace().setName(actions.get(id_hist).getNewName());
				break;
			case 7:
				trait_origin = a.getNode();
				Move(a.getNewX(), a.getNewY());
				repaint();
				break;
			}
		}
	}