How to Disable Check for updates button in Help/About in firefox 5.0

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */
#aboutDialog #updateBox { display:none!important; }

You can hide that button with code in userChrome.css below the @namespace line. * http://kb.mozillazine.org/userChrome.css * http://kb.mozillazine.org/Editing_configuration You can use the ChromEdit Plus or Stylish extension to have easier access to the customization files. * ChromEdit Plus: http://webdesigns.ms11.net/chromeditp.html ---- <pre><nowiki>@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */ #aboutDialog #updateBox { display:none!important; }</nowiki></pre> ---- You can also choose to lock the related update pref(s) to false if you want to make sure. See: * http://kb.mozillazine.org/Locking_preferences * http://kb.mozillazine.org/about:config