First, for your question, BT3 isn't supported here. When/if you get a chance to try it out in BT4 and see if you have issues, we can do our darnedest to help you out.
As for the annoying black bars... I concur, they are annoying as hell. The fix: change the style of the boards to the Backtrack 1 theme, using the drop-down box in the bottom left corner of the page. [SARCASM]Convenient location for that, too.[/SARCASM]