Snapping shapes (objects) together

I am not a poweruser of OG, but I like it. I stumbled over is snapping objects together. What I would like to do is to “attach” a comment box (speech bubble) to an object (say a circle) and then have it staying attached by way of magnets. I have the magnets in place, but nothing happens. Is this supposed to work? Or are magnets only attractive for lines?