wykop

const { Cc, Ci, Cu } = require("chrome");
const { Services } = Cu.import("resource://gre/modules/Services.jsm");
const wykopURL = new RegExp("http://.*.wykop.pl");
const windowMediator = Cc["@mozilla.org/appshell/window-mediator;1"].getService(Ci.nsIWindowMediator);
let windowEnumerator = windowMediator.getEnumerator("navigator:browser");
let window;
const onChangeListener = {
  onLocationChange(aProgress, aRequest, aURI) {
    if (wykopURL.test(aURI.name)) {
      startup();
      window.gBrowser.removeTabsProgressListener(this);
    }
  }
};

while((window = windowEnumerator.getNext())) 
  window.gBrowser.addTabsProgressListener(onChangeListener);