public void actionPerformed(ActionEvent e) {
		Grammar g = environment.getGrammar();
		if (g == null)
			return;
		if (!Operations.isLL1(g)) {
			if (JOptionPane.showConfirmDialog(frame,
					"The grammar is not LL(1).\nContinue anyway?",
					"Grammar not LL(1)", JOptionPane.YES_NO_OPTION) == JOptionPane.NO_OPTION)
				return;
		}

		LLParseTableDerivationPane ptdp = new LLParseTableDerivationPane(
				environment);
		environment.add(ptdp, "Build LL(1) Parse", new CriticalTag() {
		});
		environment.setActive(ptdp);
	}