Firefox 3.5 (Mac) - Using the Popup Blocker
This document explains how to enable and disable Firefox's popup blocker. For general information on popup blockers, see Popup Blocker - FAQ.
Click Firefox, then select Preferences.
Go to the Content tab. You can toggle the popup blocker by checking or unchecking Block pop-up windows.
Additionally, you can specify which websites are allowed to open popup windows by clicking Exceptions....