Hi Anis -

>It will more clear if you can post a gif file...

You'll get a chance to test it yourself pretty soon, it should get more clear then! :)

But it is not a very big feature - just when an arc has other curves touching it at 2 possible endpoints, it will maintain the endpoint that was closest to your mouse cursor location when you clicked on the arc to select it.

So you can control which side will stay connected by clicking closer to one side or the other when you select the arc.

- Michael