From MozillaZine Knowledge Base
This preference is removed in Firefox 31. An Add-on restoring its functionality is Classic Theme Restorer. An add-on restoring all the close button values is tabs closebuttons restored. An add-on restoring the behavior of value=2 only is No Close Buttons.
Firefox 2.0 introduced a number of refinements to its tabbed browsing UI. Among them was the addition of close buttons on tabs. This preference controls how they can be displayed on tabs.
Possible values and their effects
Display a close button on the active tab only
Display close buttons on all tabs (Default)
Don’t display any close buttons
Display a single close button at the end of the tab strip (Firefox 1.x behavior)
- This preference does not exist by default in builds earlier than 2.0rc1.
First checked in
Has an effect in
- Mozilla Firefox (nightly branch builds since 2006-06-26; 2.0)
- Bug 865826 - Remove the browser.tabs.closeButtons pref
- Bug 318168 - Improve tabbed browsing
- Bug 324227 - Implement old tab close button as a preffable option
- Bug 343061 - if browser.tabs.closeButtons == 3, you can't close tabs on pinstripe
- Bug 455990 - Close button on last open tab should be hidden