Firefox 57 and later do not support any API to make this extension work. If you prefer your browser tabs without close buttons, you can make it work by adding a custom userChrome.css
file to your Firefox profile:
- Find your profile folder
- Create a directory called
chrome
inside it if one does not already exist - Create a file named
userChrome.css
in the new directory Add the following CSS code to it:
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); .tab-close-button { display: none !important; }
- Open "Advanced Preferences" by typing
about:config
in the address bar. - Search for
toolkit.legacyUserProfileCustomizations.stylesheets
and set it totrue
. - Restart Firefox
In Firefox 31, the browser.tabs.closeButtons option was removed. This restartless addon forces what previously used to be a value of 2 for that option: no close buttons on any tabs.