Block show the default VtigerCRM Confirmation box to let them decide something.
You could configure the text, the User see.
This configuration result into this in Frontend:

Enter your comment. Wiki syntax is allowed:
   ____   ___    ____   __ __  __  __
  /  _/  / _ \  / __/  / //_/ / / / /
 _/ /   / // / / _/   / ,<   / /_/ / 
/___/  /____/ /_/    /_/|_|  \____/