Is there a way to split the browser action popup in tabs, as if it were an external page (window)?

I was wondering if there’s a way to divide the popup (that appears after clicking on the browser action in the toolbar) in tabs, as if it were a new, standard Firefox window.

You can build your own tabbing system, sure. It’s contents are just a webpage, and webpages can have tabs with separate content in them.

But we just specify just an HTML page in the browser_action section of the manifest. For “tabs” I mean like those used by all browsers. Just with a simple HTML page I can’t get how I could do that.

You can include all the content of your tabs in the same html page, or you can use iframes. What I’m talking about is something similar to the example built at https://www.w3.org/Style/Examples/007/target.en.html

Note that the popup is only loaded while it’s open, so all the contents of it get destroyed (like closing a tab) whenever you close it.

Thanks for your idea, but that’s not what I’m looking for. I don’t consider those in your example to be tabs, they’re just sections of a website. I was meaning true tabs like those of browsers, to have different context for each of them. iframes don’t suite well, also, because I’d put inside of them content from websites that, since it’d be rendered inside an iframe, gets automatically blocked.

Popups have a maximum size of 800x600 pixels.
If you want to create a browser inside the browser, then action popups aren’t a good place to do that.