Loading an iframe

Is there anyway that I can show a loading sign when an iframe is loading? The vaadin loading sign disappears immediately because it has rendered the iframe, its job is done, but the page still has to load.

I embed the iframe like this:

    e = new Embedded("", new ExternalResource(
                "http://www.google.com"));
        e.setType(Embedded.TYPE_BROWSER);
        e.setWidth("100%");
        e.setHeight("400px");
        addComponent(e);

I have tried enabling and disabling a progress indicator after I add the iframe, but I think that once the iframe element has loaded it will dissappear,

any advice would help thanks!