Bug 868322 introduces event pages. They have access to launch(url[, message]) which does: 1) If the url is not open in a tab, open it. 2) Send all instances of the URL (multiple tabs with same URL receive message), a system message of type 'launched' with the message as |message| This disallows the case where event pages want to send a message to a visible page, only if the page is open. I can see a class of situations for which event pages are very useful, where the lack of this feature causes problems. I was creating a simple chat room example using push, whose structure is: 1) The event page does network I/O based on push notifications and updates the local IndexedDB store. 2) The chat UI reads from this IDB and updates the messages list. When the UI is open, the event page can call launch() and have the UI update. But when the UI is closed, the behaviour is that event page should not call launched(), but just update the database in the background. But since the event page doesn't know if a UI is present, it cannot decide whether to call launch() or not.

https://bugzilla.mozilla.org/show_bug.cgi?id=1472046 Move all DOM bugs that haven’t been updated in more than 3 years and has no one currently assigned to P5. If you have questions, please contact :mdaly.