Refresh triggers Window.CloseEvent?

With this code, when using the Refresh button in the browser, CloseEvents are generated (with Vaadin 6.8.2). Is it possible to suppress these spurious events or distinguish them from correct CloseEvents, when the browser window is being actually closed?

public class MyVaadinApplication extends Application {
	public void init() {
		final Window window = new Window("My Vaadin Application");
		window.addListener(new Window.CloseListener() {
			public void windowClose(final CloseEvent e) {
				System.out.println("Closing: " + window.getName() + ": " + e);

This question was already asked in disguised form in April 2012 ("
Listner close and Behavior F5-button.
"), but no answer has been provided.

I know that this logic has completely changed with Vaadin 7, but am actually looking for a solution in Vaadin 6.