This document explains how to enable and disable Firefox's popup blocker for versions 3.5 and higher. For general information on popup blockers, see Popup Blocker - FAQ.
Menu selections vary by Firefox version.
Firefox 4.0 or earlier: Click Tools, then select Options.
Firefox 4.0 - 28.0.1: Click the orange Firefox button at the top left, then select Options > Options.
*Note: If the Menu Bar is visible in 4.0 or later, see instructions above.
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....