Testing updates of persistent popups from the same file: origin.
On first load, the popup triggers a load event you can
listen for to know when it's safe to update the popup's content.
But on reload, the load event is never triggered;
so instead of listening for load,
call window.opener.postMessage("Loaded"); from the
popup to signal when it's safe to update content.
Go to Page 2 to make sure this really works across pages.