Direct output to alternate location

[bear]

If a link is targeted to an iframe, can the linked page create or do
anything that is NOT constrained within the iframe?

I have links targeted to a tiny (1-pixel by 1-pixel) iframe because I want
the linked page's output to be "invisible" (not change the main application
page) UNLESS it has to display a warning message to the user. But when the
linked page creates a pop up window or alert to display a message it doesn't
appear, presumably because it's being created inside the "invisible" iframe
too?

So can javascript do something on the linked page to say, "make this new
window appear outside the iframe, over all other pages"?

Thanks.