Works perfectly Rated 5 out of 5 stars
Many thanks! I was deeply dismayed to find that the update from Thunderbird 3.1.6 to 3.1.7 not only broke keyconfig and Rewrap Toolbar Button, but Nightly Tester Tools stopped showing its force addon compatibility button. I upgraded Nightly Tester Tools from 2.something to 3.0, no change, utterly refused to let me unlock the addons that, after all, were still working perfectly while incompatible.
So I ditched it and installed this in its place, and it's working. That will keep me wrapping and avoiding accidental quits for the foreseeable future.
 keyconfig is (almost) ESSENTIAL for anyone who also uses Outlook, as Outlook's mark as unread is ^Q, whereas Thunderbird uses that for Quit!! Incredibly annoying. (I qualify that with "almost" because, after all, I can also resolve this trivially with AutoHotkey like where I've make ^D exit console windows, ^W close JujuEdit etc. Outlook has some truly lousy shortcuts.)
 This is useful since Thunderbird's message editor stinks, both for HTML and for plain text. I still miss Mac Outlook Express, all these years on. Dynamic quote colouring, intelligent auto rewrap etc. Sadly one of my add-ons has broken even the blue colouration for quoted text in plain-text e-mail ... never figured out quite what went wrong there, but that "feature" was hopelessly broken even when it did "work" (kept getting the colour wrong)