OmniGraffle: How to make line terminators connect to Center of objects, not to the edges of the objects?
You can use the magnet editor to create a magnet wherever you want on the object.  Luckily, the center of objects is a natural &quot;snap to&quot; location for the magnet.
Once you have a magnet set in the center, you can easily terminate your lines at that magnet.
Tedious, yes.  But, possible.