How Sessions are treated with respected to different browsers and windows ?

In context of multiple windows here is the quote from the servlet spec. How the session is treated depends on the browser processes.

From Spec:

Client Semantics

Due to the fact that cookies or SSL certificates are typically controlled by the Web browser process and are not associated with any particular window of the browser, requests from all windows of a client application to a servlet container might be part of the same session. For maximum portability, the Developer should always assumethat all windows of a client are participating in the same session.