I updated the ticket title. The need is very similar to XWIKI-16361: when modifications are made to a user that may results in scripts not working anymore because of the loss of rights of that user, there should be a warning and the admin making the group membership change should have the opportunity to fix the situation to keep the scripts working. XWIKI-16361 handles the case of a user losing rights because it's deleted, this issue is about a user losing rights because they change group.