Testing updates of persistent popups from the same file: origin.
On first load, the popup triggers a "load" event and you can
listen for it to know when it's safe to update the popup's content.
But on reload, the load event is never triggered, so you need to
call window.opener.postMessage("Loaded");
from the
popup to signal when it's safe to update content.
Go back to Page 1 to make sure this really works across pages.