Pop-up blocker
This document explains all of the settings available in Mozilla Firefox for controlling pop-ups.
Taula de continguts
- What are Pop-ups?
- Pop-up Blocker OptionsPreferences
- Pop-ups not being blocked
- Is the pop-up coming from Firefox?
- Is the pop-up blocker on and enabled for this site?
- Is the pop-up shown after a mouse click or a key press?
- Is it a true pop-up window?
What are 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:
- Allow/Block pop-ups for this site
- Edit Pop-up Blocker OptionsPreferences…
- Don't show this message when pop-ups are blocked
- (show the blocked pop-up)
Blocking pop-ups doesn't always work: Although Firefox blocks most pop-ups, some websites may show pop-ups using uncovered methods, even when blocked.
Pop-up Blocker OptionsPreferences
To access the Pop-up Blocker settings:
- At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
- Select the Content panel.
From there, you can do the following things:
- Block pop-up windows: Deselect this optionpreference to disable the pop-up blocker altogether.
- : This is a list of sites that you want to allow to display pop-ups.
The dialog has the following choices:- Allow: Click this to add a website to the exceptions list.
- Remove Site: Click this to remove a website from the exceptions list.
- Remove All Sites: Click this to remove all of the websites in the exceptions list.
Note: Blocking pop-ups may not always work and may interfere with some websites. For more information about blocking pop-ups, see What are Pop-ups.
Pop-ups not being blocked
Is the pop-up coming from Firefox?
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.
- A Firefox icon and "Mozilla Firefox" in the title: keep reading below.
- Everything else: you may have malware on your computer that causes the pop-ups. Scan your computer for viruses and spyware.

This pop-up comes from Firefox. It has a Firefox icon and the text Mozilla Firefox.
Is the pop-up blocker on and enabled for this site?
- At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
- Select the Content panel.
- Make sure the Block pop-up windows checkbox is checked.
- To the right of Block pop-up windows, click the button. A dialog will appear that shows all the sites that are allowed to show pop-ups.
- If the site that's opening pop-ups is in the list, select it and press .
- Click Close the Allowed Sites - Pop-ups window.
- Click Close the preferences window.
Is the pop-up shown after a mouse click or a key press?
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 websites need to work.
Is it a true pop-up window?
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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