Destroyed session with closed browser

[eluser]babazumbula[/eluser]
Hi,
I made Login application,and loguot is via sess_destroy() function. It works well. However session doesn't get destroyed when browser is closed. This is what I want to achieve. If user forget logout link,I want session to be destroyed with each closing browser.
I've been looking through user guide, but seems like can't find the answer.