The Mozilla website hosts several add-on directories for Mozilla software such as those for Firefox or Thunderbird. If you look at these add-ons you will eventually notice that not all add-ons are compatible with the version of Firefox or Thunderbird that you are using.
The Mozilla website will even display if the add-on is compatible with Firefox if you visit the website with that web browser. The text that will appear states that "this version is for older versions of Firefox" which means it cannot be installed directly.
Experienced users know the workarounds that can force compatibility with a specific version of Firefox or Thunderbird. But what if that is not always necessary?
What if the version that is displayed in the directory listing or on individual add-on pages is not the latest version?
That's right. In my quest to uncover why the date sorting on the Mozilla website did not sort the add-ons by the dates displayed, I uncovered the reason for this and the secret that newer versions are sometimes available but not displayed.
Take the coLT add-on for example. Its profile page states that the add-on is compatible with Firefox: 1.5 – 3.5.* only which removes the install button from the page if you visit it with Firefox 3.6 or later. You will also notice the date the add-on was last updated which in this case is listed as August 2009.
Update: The pages of add-ons on Mozilla have been redesigned. You need to scroll down to the Version Information section now, and click on "see complete version history" to display older versions but also any new version that is not listed yet on the main page. End
If you scroll down the page you come to a link called view older versions. It will still state that the latest version was released in August and that the latest version is 2.4.5.
The page that lists the older versions on the other hand reveals something interesting. This page has been designed to provide users with access to older versions if the latest version is causing troubles for them. The first version on that page however is 2.4.6, the release date is listed as December 2 and the compatibility is listed as 1.5 – 3.6.*.
The version of the add-on listed there is compatible with Firefox 3.6 while the version on the profile page and in the directory was not. The add-on can therefore be installed without forcing compatibility.
These new versions sometimes even contain bug fixes or new features that the older but more prominent versions do not offer.
My guess is that it has something to do with certifying the newest version. Some parameters are already added to the database (like the date) while others are not until it is certified. This method works best if add-ons are sorted by date.
Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.