Add-on SDK: to Certificate Viewer window

gistfile1.js

let { events: windowEvents } = require('sdk/window/events');

let { on } = require('sdk/event/core');
let { filter } = require('sdk/event/utils');

let ready = filter(windowEvents, ({type}) => type === 'DOMContentLoaded');
let certificateWindows = filter(ready, ({target}) =>
  target.document.documentElement.mozMatchesSelector('dialog#certDetails'));

on(certificateWindows, 'data', ({target: window}) => {
  let { document } = window;

  console.log(document.documentElement.outerHTML)
}, true);