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Understanding the browser.tabs.warnOnOpen about:config Entry in Firefox



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about:config Entries

browser.tabs.warnOnOpen is one of hundreds of Firefox configuration options, or Preferences, accessed by entering about:config in the browser's address bar.

Preference Details

Category: browser
Preference Name: browser.tabs.warnOnOpen
Default Status: default
Type: boolean
Default Value: true


The browser.tabs.warnOnOpen Preference in Firefox's about:config interface allows the user to toggle the warning message that appears whenever an attempt is made to open a large number of tabs simultaneously. The actual number is specified in the browser.tabs.maxOpenBeforeWarn preference.

How to Use browser.tabs.warnOnOpen

The value of browser.tabs.warnOnOpen can be set to either true or false. When set to true, Firefox will display a warning message (which requires user confirmation) if an attempt is made to open a large number of tabs at once. When set to false, this warning message will never be displayed.

To modify the value of browser.tabs.warnOnOpen, follow these steps:

  • Open your Firefox browser.
  • Type about:config in your browser's address (or URL) bar.
  • Hit Enter.
  • A list of Firefox Preferences should now be displayed. Locate the entry with a Preference Name value of browser.tabs.warnOnOpen.
  • Double click on this entry. Notice that the Value column is immediately changed to either true or false, depending on what the previous value was. To change it back, simply double click on the entry again.

Related about:config Entries

The following entries are related to the browser.tabs.warnOnOpen entry:

browser.tabs.warnOnOpen Related Content

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