According to Quim in the comments of Bug 3929, someone needs to open a specific bug asking that the toolbar(s) get moved to the side instead of the bottom, or even better, a way to move the toolbar(s) to any edge (left, right, top, bottom) the user prefers. And you also need to provide a patch to do it, so that the osso-xterm guy, Gabriel, can add it.

(Well, there's no guarantee that he'll add it, but I wish I was a programmer so I could try anyway.)

Any programmers out there able to provide this patch? Or is there a version already out there that can have the relevant code diff'ed out and posted as a patch?