postgres transaction php trigger rollback

Hi, 1. User clicks edit_record.php page 2. Page starts transaction and SELECT FOR UPDATE (say this is PostgreSQL) 3. User instead of clicking Submit/Reset buttons goes to www.boyplay.com 4. Other users can not edit this record because it was locked. If somebody can give me an idea how to trigger Rollback on server. I see the only solution here -- using sessions with timeout equals to reasonable value for each particular page which requires transaction. Thank you, Igor