Some people prefer to be warned when a website wants to set a cookie. Even though the option does not appear in Firefox, this is another feature from the Mozilla Application Suite that is in the back-end code for Firefox.
To enable cookie warnings in Firefox:
Enter about:config in the location bar.
Right-click anywhere within the list of preferences and select New -> Boolean.
When you get asked to enter the preference name, enter:
network.cookie.warnAboutCookies
Set the value to true.
Here’s a screenshot:
Slight problem… Setting the value back to ‘false’ doesn’t disable the alert.
Good catch.
I think there just may be a UI for it. In Tools -> Options -> Privacy -> Cookies, there’s a dropdown menu. You can set it to anything but “Ask me every time.”