How Does Firebug Get Contents From an IFrame?

Question

I am well aware of cross-origin restrictions when it comes to browsers, but what I don't get is how Firebug can get and display the HTML from an iframe with this restriction in place. Is there something plugins have access to that lets it get around this?

Answer 1

Plugins have access to quite a bit. They're not considered cross-origin, they're considered a part of your browser.