If you place an intermediate event at the border of an activity during modeling, a connection is automatically created.
If you now move the activity that is not fully wrapped by an intermediate event, the intermediate event placed on the connection is also moved. The graphic shows how this scenario is handled.
If you place an intermediate event within an activity during modeling, it is automatically placed on the border and can only be moved on the border. You can no longer move the intermediate event to an area outside the activity.