Time Blocking?

When I enable the time blocking, for example 1 hour per day -  while reaching this 1 hour quota the system is giving an alert an locks the computer, but the child can again unlock and work for few minuts, like this the child can misuse the few minutes grace time.  

 

Is there a possibility to set it to logoff the user and not allow any grace period?

 

When I enable the time blocking, for example 1 hour per day -  while reaching this 1 hour quota the system is giving an alert an locks the computer, but the child can again unlock and work for few minuts, like this the child can misuse the few minutes grace time.  

 

Is there a possibility to set it to logoff the user and not allow any grace period?