Problem with cookie expiration set to 0 in IE8

I have found a fairly significant issue with IE8 with regard to setting cookie expirations to 0 (so as to log a user out when they close the browser). It seems that each new tab or window is counted as a new session, so if a user opens a page on the site in a new tab/window, they have to login again unless they selected the option to stay logged in, which makes the cookie persistent and doesn't cause any problems. There has got to be a way to make this work like it should and always has开发者_开发知识库 in the past without forcing my users to stay logged in even after they close the browser. If it matters, I am setting the cookies from pHP like this:

setcookie("username",$username,0," ",".example.com");

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the issue could be the space in the path field. this attribute should be unspecified or should be a valid path like /home. try specifying an empty string ('') instead of space.

could also be a caching thing, i.e. the login page may appear to be unauthenticated because the content was cached. session_cache_limiter('nocache') in php would instruct the browser not to cache anything (when using sessions), which is the same as setting:

Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache

to omit the path, you can pass '' (empty string) or null to setcookie for that param. or use something like '/' to indicate the entire site.

ie8 windows and tabs share the same session unless the user selects "File -> New Session" or runs iexplore.exe -nomerge explicitly.