How to Implement the help button with question mark icon on the WizardDialog

I have implemented a Wizard and WizardPage. I noticed that it has a help button with question mark icon. I would like to open a browser internal/external with a static url(www.stackoverflow.com). I have tried a few things but I couldn't find what gets executed when the button is clicked.

1. I have implemented the HelpListener on both WIZARD & WIZARDPAGE; but could not get the method to be invoked when I click on the button.

   public void helpRequested(HelpEvent e) { PlatformUI.getWorkbench().getBrowserSupport().getExternalBrowser().openURL(new URL("http://www.stackoverflow.com")); }

2. In the WIZARD constructor I have setHelpAvailable(true); and it gives me the Help button with the text.

3. I also tried the HandleEvent in the WIZARDPAGE with SWT.Help event type but again nothing happened.

I am not sure if & how I can add listener to this button? and How I could implement to open a browser by clicking on this button.

Please advice. Thanks in advance.