This document explains all of the optionspreferences available in Mozilla Firefox for controlling pop-ups.
Pop-up windows, or pop-ups, are windows that appear automatically without your permission. They vary in size but usually don't cover the whole screen. Some pop-ups open on top of the current Firefox window, while others appear underneath Firefox (pop-unders).
Firefox allows you to control both pop-ups and popunders through the Content panel in the OptionsPreferences window. Pop-up blocking is turned on by default, so you don't have to worry about enabling it to prevent pop-ups from appearing in Firefox.
When blocking a pop-up, Firefox displays an information bar, as well as an icon 
in the status bar.


When you click either the button in the information bar or the icon in the status bar, a menu is displayed with the following choices:
Blocking pop-ups doesn't always work: Although Firefox blocks most pop-ups, some web sites may show pop-ups using uncovered methods, even when blocked.
To access the Pop-up Blocker OptionsPreferences:
From there, you can do the following things:


Note: Blocking pop-ups may not always work and may interfere with some web sites. For more information about blocking pop-ups, see What are Pop-ups.
The pop-up may not actually be coming from Firefox. You can determine where the pop-up is coming from by the icons it has and the title at the top.

This pop-up comes from Firefox. It has a Firefox icon and the text Mozilla Firefox.
Certain events, such as clicking or pressing a key, can spawn pop-ups regardless of if the pop-up blocker is on. This is so that Firefox doesn't block pop-ups that web sites need to work.
Sometimes ads are designed to look like windows, but really aren't. Firefox's pop-up blocker can't stop these ads.

This page has fake pop-up windows. Some signs include the color of the title bars being wrong and an incorrect or missing icon in the top left.
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