If a mouse click is performed, the circle follows the mouse, even if the key is released. This makes it more difficult to see the point, where the mouse was initially clicked. There's also no visual indication to cue to distinguish between a click and the start of mouse dragging.
I'd suggest the following behaviour:
Mouse button is pressed down: Circle is rendered and expanded to stop scale, but no opacity and border width changes are triggered.
Mouse is dragged: The circle moves with the pointer and remains at stop scale, start border and start opacity.
Mouse button is released: The circle stops moving, the animation to stop border and stop opacity is started.
This change may lead to several circles shown at the same time.
If a mouse click is performed, the circle follows the mouse, even if the key is released. This makes it more difficult to see the point, where the mouse was initially clicked. There's also no visual indication to cue to distinguish between a click and the start of mouse dragging.
I'd suggest the following behaviour:
This change may lead to several circles shown at the same time.