I remember how long it took us to get that hack implemented last time, to put the extra link on the "transferring" page.
My personal recommendation has always been and continues to be to always open threads in new windows, so that returning to the forum listing after posting a reply is a matter of a contol-tab/single click/command-w (depending on my mood

).
I will pass the request on to parallax, and ask him how difficult it would be. in general, we want to implement as few hacks as possible, since every additional hack makes future upgrades more difficult. And this does not strike me as a serious issue at all, since it is so easy to design for yourself a forum-use workflow which side-steps the "problem."