After a long fight, to use a jquery code on an angular page. ended up here.
Still does not work with Firefox 26. Please update this to work, as it sounds very useful.
Does not work with Firefox 22 in Gnome-shell (Fedora); though, initially it does display a prompt to select external editor. Just wanted to leave a heads-up to anyone looking for an in-browser editor-this is not the one; at least it wasn't for me.
I like it when an extension does exactly what it is supposed to do, nothing more nothing less!