Oxymoronical

Back in the mists of time I wrote some code to make nightly testers’ lives easier by giving them a simple preference to flip if they wanted to be able to install and use incompatible extensions. It’s been more than three years since then and the use of this preference has grown beyond its original use. It is now something recommended to regular users everywhere from forums to comments in news articles as a way to use their extensions in the new major Firefox releases.

Don’t get me wrong, letting users upgrade sooner than they otherwise might is a good thing, but the preference is a dangerous beast. It is pretty simple for a user to set the preference and then forget about it leaving them able to install incompatible extensions that break their Firefox without realising it. This costs Mozilla time as well since we get quite a number of bug and crash reports to look at that turn out to be caused by extensions that are dutifully marked incompatible with the user’s Firefox.

We’ve been mulling over ways to change this for a while but now we’ve actually gone and done something about it. We still want nightly testers and early adopters to be able to use incompatible extensions if they need to but we also want to make the preference not be a one shot deal that lasts till the end of time. The plan we’ve come up with is to change the preference’s name with the Firefox version, so for Firefox 3.6 (and all security releases) the preference will be extensions.checkCompatibility.3.6. When switching to a future 3.7 testers and users will have to set a new pref extensions.checkCompatibility.3.7 to say they still accept the risks of running with incompatible stuff.

Nightly users will have to make the changes slightly more often since the preference will also track whether the version is one of the development alphas or betas, so for the 3.6 betas the preference would be extensions.checkCompatibility.3.6b, for the current trunk extensions.checkCompatibility.3.7a. These are just normal preferences of course, if you frequently switch between different Firefox versions you can just set both necessary preferences. The change should land on the trunk in the next day or so and then the 3.6 builds a day or so after that.

There is just one oddity, if you’re testing nightlies and you update to a build with the change then you likely won’t notice any of your extensions disabling themselves, that won’t happen till either you toggle the pref or you switch to a build with a different Firefox version number in it.

Update: For more in-depth information this change was made in bug 521905.