public void actionPerformed(ActionEvent e) {
		Grammar g = environment.getGrammar();
		if (g == null)
			return;
		LRParseTableDerivationPane ptdp = new LRParseTableDerivationPane(
				environment);
        if(ptdp.getAugmentedGrammar() == null) return;
		environment.add(ptdp, "Build SLR(1) Parse", new CriticalTag() {
		});
		environment.setActive(ptdp);
	}