All tests are outputed to developer javascript console (try F12 hotkey)
Script for this request https://www.reddit.com/r/GreaseMonkey/comments/2wb05u/troubleshooting_dev_tampermonkey_gm/
My previous version of this script was here http://userscripts.org/scripts/review/186638 ( http://userscripts-mirror.org/scripts/review/186638 )
Just showing some properties of GM_xmlhttpRequest .
