Firefox addon code for every tab open

I'm attaching some functionality to javascript by doing a firefox addon. However when coding in chrome and listening to the load event in the chrome overlay t开发者_高级运维riggers for every loaded tab, but the "content" variable only points to the tab currently in the foreground.

How can I get the content of every tab upon document load from a firefox addon?

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Assuming you are using code like this to be told every time a new page loads (which is what you really want to use if you aren't), aEvent.originalTarget is a reference to the document that the event was for.