Gallery Password cookie expiry

[exposed]

Is there code that can be added to ensure "gallery protection cookies" either expire after so many minutes, or upon browser closure? At the moment "gallery protect" cookies persist indefinitely. Or expire after user account log-out. Non user-account browsers who receive and use a gallery protection password (once) has the cookie persist forever. They do not know this, expect this, or have any way to expire the cookie.

Further details on here......
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