JButton startButton = new JButton("Start");
		startButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
				model.start();
			}
		});

class MyModel extends PropertyChangeSupport{
    State state;

    void start(){
            setState(STARTED);
    }
 
    void setState(State s){
        State old =  this.state;
        this.state = s;
        firePropertyChanged("state", old, s);
    }
}


model.addPropertyChangeListener("state", new PropertyChangeListener(){
         void propertyChanged(PropertyChangeEvent pce){
                 anotherButton.setEnabled(pce.getNewValue() == STARTED);
         }
})