Firefox has a very useful setting to block installation of add-ons, which I've taken to setting after installing some of the fundamental, safe add-ons. In abou

Firefox has a very useful setting to block installation of add-ons, which I've taken to setting after installing some of the fundamental, safe add-ons. In about:config, create a boolean value xpinstall.enabled and set false. This does protect against those browser toolbars that people somehow manage to install. However there is apparently a UI feature that prompts to re-enable installation ( though I've never seen this ): https://bugzilla.mozilla.org/show_bug.cgi?id=668999 https://bugzilla.mozilla.org/show_bug.cgi?id=668999 It