According to ISTQB regression testing is testing of a 
previously tested program following modification to ensure 
that defects have not been introduced or uncovered in 
unchanged areas of the software, as a result of the changes 
made. It is performed when the software or its environment 
is changed.

Here only the defects which were raised by you will be 
picked up and tested.
 
Go to that perticular window where you found the defect and 
verify if it is working or not