A circle is resized if grabbed from the inside, or moved if grabbed from the outside. When being resized, the circles centre will remain put, while it changes size to keep its circumference under the mouse. When being moved, the circles size will remain constant while the whole circle will move to follow the mouse.
To grab the circle from the inside, approach the circumference from inside the circle. To grab it from the outside, approach the circumference from outside the circle.
| grabbing the circle from the outside moves the whole circle |
| grabbing the circle from the inside resizes the circle |