How to hide closing session pop-up window in Portal 7.3

Hi Experts,

As per client requirement need to hide the closing session pop-up window in portal 7.3. Every-time the pop-up window is appearing in the right top corner while closing any portal windows in the browser.

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I tried to find out the solution for this, but no luck. Also i got SAP Note for disable session management (1830713 - Disabling Session Management Alerts in 7.3). But it is not working for this scenario.

Please help me to hide this window in the portal 7.3.

Regards,

Prakash T