private static String getStateString(MinimizeTreeNode node) {
		State[] states = (State[]) node.getUserObject();
		int[] ids = new int[states.length];
		for (int i = 0; i < ids.length; i++)
			ids[i] = states[i].getID();
		Arrays.sort(ids);
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < ids.length; i++) {
			if (i != 0)
				buffer.append(", ");
			buffer.append(ids[i]);
		}
		return buffer.toString();
	}