Extrude the selected vertices into a roundover bevel.
This action is very similar to the Extrude Bevel action except that a rounded bevel is created on the set of curves. The extrusion takes place on the side of the plane in which the 3D Cursor lies. It extends away from the curve until it reaches the position of the 3D Cursor.
Curves that lie inside other curves are considered to be holes, and they will bevel with the opposite angle to (but to the same plane as) the outer curves. The selected vertices must form a set of closed curves if the Round Over function is to work properly.
If the action gets stuck, it may be aborted by pressing the ESC key.