Information
This feature controls popups that are initiated by plug-ins.
Rationale:
Disabling plug-in popups (except from white-listed sites) from being displayed, can guard against attacks that are launched using a pop-up.
Impact:
Pop-ups will not be displayed.
Solution
To establish the recommended configuration, set privacy.popups.disable_from_plugins to 2:
Type about:config in the address bar
Type privacy.popups.disable_from_plugins in the filter
Ensure the setting is set as prescribed.
OR
Open the mozilla.cfg file in the installation directory with a text editor
Add the following lines to mozilla.cfg:
lockPref('privacy.popups.disable_from_plugins', 2)
Default Value:
3