Comment 65 for bug 10883

The shift-click on the "Reply" and "Forward" buttons has been working for me for quite some time now, although it hadn't been even after it was reported elsewhere to be working. So I would expect it *should* work for you at this point (if it doesn't, that could be a different bug)

Of course, getting any new bugs fixed *now* may be more problematic, now that Mozilla has decided to throw the TB developers at the bloated and unstable disaster that is the current-day Firefox.