Cute. Spent a bit of time trying to figure out how to get an arrow: It's not obvious that you need to drag to get an arrow object, because if you just click without dragging, all the other objects will create a new instance at top left. I started out assuming that the UI would be select the object, then click to make a new instance where you wanted it. So, once an object appeared, I thought the intended UI was, click to get object, move it to where you wanted. I think you need to either not create a new object unless the user does drag, so they understand that something more is required (which is how visio seems to do it) or make 'new instance at top left' work for all objects.