Tho i struggled to understand id I was actually selecting a circle. Because no state change actually made it obvious, and when that circle was been moved around, I didn't know if it was, I had to experiment, and then work with that understanding, so half of these moves or more were wasted to finding out.
This is good job. Tried it out. I love the general interface, and the ease of file uploads, and edits. I guess this is a natural feel from the fact everything is client side!