This is accomplished via the New Session option, which makes it possible to log onto Web sites that track your identity across different tabs--like Gmail.
Here's how to utilize this IE8 feature:
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1. Open Internet Explorer 8 and login to your Gmail account. Make sure the Remember Me option is unchecked when you sign in.
2. Press Alt-F, I, and then hit Enter. This will open a new Internet Explorer session (which for all intents and purposes is the same as a new IE window).
3. Open Gmail and sign in with different account, again making sure to uncheck Remember Me.