Portal session does not close when browser tab is closed

hi All,

we are on sap nw portal version 7.4. When I close the browser tab in a multiple tab browser the session does not close.

The same is not happening if I close the browser window.

So I tried retrieving mysapsso2 cookie and modifying its setMaxAge but still the sessions are not getting closed.

Has any of you faced this issue before?? If yes please let me know what can be done?

Thanks ,