[news.eclipse.platform.rcp] new to RCP, problems with jface preference

[poldoj2002@xxxxxxxxx (poldoj2002@xxxxxxxxx )]

Hi all!
I'm trying to receiving notification of preference changes. I've made a 
simple jface application that with a preference dialog. I only wish to 
display a simple output string at each preference change made by the user 
with the dialog. So far no luck with this code:
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import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.CoolBarManager;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.action.StatusLineManager;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.preference.PreferenceStore;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jface.window.ApplicationWindow;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class Main extends ApplicationWindow implements 
IPropertyChangeListener {
	private IPreferenceStore ps;
	private PreferencesAction _preferencesAction = new 
PreferencesAction(this);

	/**
	 * Create the application window
	 */
	public Main() {
		super(null);
		createActions();
		addCoolBar(SWT.FLAT);
		addMenuBar();
		addStatusLine();
		ps = new PreferenceStore("my.properties");
		ps.addPropertyChangeListener(this);
	}

	public void propertyChange(PropertyChangeEvent event) {

		System.out.println("changes");

	}

	/**
	 * Create contents of the application window
	 * @param parent
	 */
	@Override
	protected Control createContents(Composite parent) {
		Composite container = new Composite(parent, SWT.NONE);
		//
		return container;
	}

	/**
	 * Create the actions
	 */
	private void createActions() {

		// Create the actions
	}

	/**
	 * Create the menu manager
	 * @return the menu manager
	 */
	@Override
	protected MenuManager createMenuManager() {
		MenuManager menuManager = new MenuManager("menu");

		menuManager.add(_preferencesAction);
		return menuManager;
	}

	/**
	 * Create the coolbar manager
	 * @return the coolbar manager
	 */
	@Override
	protected CoolBarManager createCoolBarManager(int style) {
		CoolBarManager coolBarManager = new CoolBarManager(style);
		return coolBarManager;
	}

	/**
	 * Create the status line manager
	 * @return the status line manager
	 */
	@Override
	protected StatusLineManager createStatusLineManager() {
		StatusLineManager statusLineManager = new StatusLineManager();
		statusLineManager.setMessage(null, "");
		return statusLineManager;
	}

	/**
	 * Launch the application
	 * @param args
	 */
	public static void main(String args[]) {
		try {
			Main window = new Main();
			window.setBlockOnOpen(true);
			window.open();
			Display.getCurrent().dispose();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * Configure the shell
	 * @param newShell
	 */
	@Override
	protected void configureShell(Shell newShell) {
		super.configureShell(newShell);
		newShell.setText("New Application");
	}

	/**
	 * Return the initial size of the window
	 */
	@Override
	protected Point getInitialSize() {
		return new Point(500, 375);
	}

}
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Thanks in advance for your help.