When I select a shape that has a comment attached to it, despite "lassoing" (or multiselecting) the shape and the comment, moving the selection does not move the comment, so the comment becomes disembodied from the object to which the comment applies. This is probably a bug but I think I'm actually asking for a feature in which a comment is connected to a shape so it will move with the shape despite not being multi-selected. I can see the case where you would want a comment to float on the background but in most cases, I comment on shapes.