getting current page content (after DOM mutate)

I may be missing something very obvious here, but:

I want to read the current page in Firefox when the page has largely
been laid out using AJAX/Javascript. Specially I want the current text
(a la IE's innerText) for page generated by Javascript.

Say the current page is my GMail inbox. Now, if I dump
window.content.document.body.innerHTML, I will only get the static
HTML as downloaded from GMail which is fairly minimal as its fleshed
out by later AJAX requests. I don't get the updated HTML/DOM that
represents the GMail interface including all currently displayed
messages subjects, labels, etc. (This is just an example, it's not
only GMail I'm after, it's any page created dynamically on the client
side) I want the actual contents of the current DOM even if mutated.
Is this possible?