Userscripts.org

Hey guys, I'm looking for some help on this script. As far as I'm aware, you can't actually grab the body element UNLESS they specified a body id, which is different for each page generally. For the script, I want an off and on button that can toggle the page editing. I want it at the top of the page, so I could use something like document.body.insertBefore(editor, body.nextSibling) or something like that. If it's possible, please could somebody show me how? It will improve the script by miles.