@Override
	public void actionPerformed(ActionEvent e) {
		String which = e.getActionCommand();
		if (which.equals("next")) {
			handleNext();
		} else if (which.equals("back")) {
			handleBack();
		} else if (which.equals("last")) {
			handleLast();
		} else if (which.equals("first")) {
			handleFirst();
		} else if (which.equals("open")) {
			handleOpen();
		} else if (which.equals("exit")) {
			handleExit();
		}
	}