This document explains how to enable and disable Firefox's popup blocker. For general information on popup blockers, see Popup Blocker - FAQ. Note: Users should normally be prompted by the app when a popup tries to open. This document is for setting the default option.
In the search bar, type about:config.
In the new search bar, search for dom.disable_open_during_load and locate the corresponding option.
Click the toggle to change the setting to true or false. True: popups are enabled. False: popups are disabled.