Removing sub Window does strange behaviour

Vaadin 6 / 7 / 8 Framework UI
1

I have a requirement Where in i have show a popupwindow and when user closes the subwindow i have to navigate to another view. I used window close listener to achieve this.
When the user closes the subwindow my application navigates to the required page but in the new page i still see a small subwindow which it should not.
Here is the method i have written

private void handleRiskDataDisplay(final ThreatInfoComponent riskData,
		final DailyTask task) {
	// TODO Auto-generated method stub
	final HCMUApplication app = (HCMUApplication) BaseApplication
			.getInstance();

	final Window popupRiskDataWindow = new Window();
	// popupWindow.addStyleName("HCMUTreatmentInfoPopupWindow");
	popupRiskDataWindow.setModal(true);
	popupRiskDataWindow.setDraggable(false);
	popupRiskDataWindow.setResizable(false);
	popupRiskDataWindow.setScrollable(false);
	popupRiskDataWindow.setClosable(true);
	popupRiskDataWindow.center();
	popupRiskDataWindow.addComponent(riskData);
	VerticalLayout content = (VerticalLayout) popupRiskDataWindow
			.getContent();
	content.setSizeUndefined();
	content.setMargin(true);

	// Add window closing listener
	popupRiskDataWindow.addListener(new Window.CloseListener() {

		private static final long serialVersionUID = 2903662733997645927L;

		@Override
		public void windowClose(CloseEvent e) {
			[b]

app.getMainWindow().removeWindow(popupRiskDataWindow);
[/b] presenter.navigateToClientView(task);
}
});
app.getMainWindow().addWindow(popupRiskDataWindow);
}

I explicity remove the window before navigation.
See the screen shots attached
12274.jpg
12275.jpg

2

Solved using

for (Window w : app.getMainWindow().getChildWindows()) {
app.getMainWindow().removeWindow(w);
}

But don’t know why two windows are getting added.