I think he's referring to TradeBar. It is an Ace addon, but there's no page for it. In any case, I'm going to bet that you just need to unlock it. If it's not obvious what slash commands you would use for this, you might want to get DeuceCommander or Niagara, each of which should give you a GUI menu that you can use to unlock the bar.
General: This addon will only work for you, if you have an english or german client! Other languages have to translate
the "locale-xxXX.lua" and send it to me (firstname.lastname@example.org; in english or better in german, please) ;)
1. Move the box by left-click and drag (only if unlocked - see "/tb locked")
/tradebar or /tb
Further help ingame by using only /tb
I've never used it, if it's bugged I don't know.
Also: Is this a FuBar plug-in? This may question may be in the wrong spot.