Issue 691 interact mac broken

@dlonie @aashish24 please review and feel free to suggest better/cleaner solutions.
@ThomasMaxwell wouldn't mind you looking this over as well and testing it against DV3D.

Just as a general style note, committed commented out code is rarely necessary. If you've removed something, the old implementation is still stored in git, and if it's new code, why add it if it isn't used? Otherwise it just clutters the codebase and gets in the way of readability.

If there is a reason to leave a commented code path in, a comment explaining why is a good idea.