General iframe question

Hi quys,
I have question which is not much vaadin related B) . But I use Vaadin and you guys are very smart so I hope you can help me.
I have Embedded component in Vaadin application which creates simple iframe like that:

URL url = new URL("some url");
	ource = new ExternalResource(url);

		iframe = new Embedded("Title", source);

When I browse inside iframe the state of inner page changes. I want that state to be persistet after I reload the page. Default behaviour is that iframe content is redrawn to init state(url).

Is it possible to track real actual url (state) of inner page inside iframe? I suppose with javascript. Do you think is it possible?

Thanks in advance for your responses.

here I am with 2nd part of the question.

I have 2 embedded components (iframes) in the Vaadin application.

I tried hide and show (setVisible() on Embedded) these iframes so only 1 iframe is displayed at time. But every time I do this hiding 1 iframe and showing 2nd iframe the content of showed one is reloaded.
Is it normal behaviour? Can I avoid it?