There was such a setting in Visio regarding line routing, but I can't find anything similar for this in OmniGraffle's settings.
It would be nice to prevent stuff like this when the magnet logic should be fairly clear (and no, they are not anchored to the magnets): http://grab.by/Dhn
It would be nice to prevent stuff like this when the magnet logic should be fairly clear (and no, they are not anchored to the magnets): http://grab.by/Dhn