Hallelujah, finally disabled OOPP. I use Firefox 9.0.1 and will not upgrade to anything that ignores my settings. Been looking for this info for years!

Question

As soon as Firefox came out with OOPP, I immediately asked how to permanently disable it and had a Firefox developer straight-up lie to me and say it couldn't be done without downgrading. Thank GOODNESS for the instructions on https://support.mozilla.org/en-US/questions/713600?page=1 Finally, finally I have excised the hated OOPP!
I run Firefox 9.0.1 and will not upgrade, ever, unless I see signs that Mozilla has radically altered its development direction and discarded most of the boneheaded, broken, anti-user development that has gone into versions more recent than Firefox 1.x. Actually making your mission statement more than an empty promise might be a good place to start.
Let's see...anything else? Oh yeah, any developer who advocates overriding or ignoring user settings, or taking control away from the user, should be kicked off the team. (and investigated as a possible Government mole, but that's a lot to ask for). I hear Konqueror and Safari are looking for new devs. It gets old fast when you try to get support and instead get haughty "You're doing it wrong, stop doing that" responses. I'm doing exactly what I intend to be doing and if you can't support that, someone else will. If you really gave a damn about your users, you might start by backporting security fixes to previous versions instead of spewing out a cacophony of incompatible new versions so rapidly you end up confusing and alienating users and making them switch updates off entirely. I mean seriously, what happens when Firefox hits triple digits? You could stick a decimal in front of it, and name that build after a historic baseball player who had that batting average. But even then you will run out of players in a few months.
It's truly sad. I switched to Firefox because it was the best browser. But Firefox has been backsliding horribly since around 2.0, and the other browsers seem to be in about the same boat. Firefox IS still the best browser - but only if you use an ancient, unsupported version. That's a big problem.

Answer 1

Using an obsolete version released [http://www.mozilla.org/firefox/9.0.1/releasenotes/ December 11th 2011] is the exact definition of downgrading. It exposes your system to all the security vulnerabilities that have been fixed since then.
* https://www.mozilla.org/security/known-vulnerabilities/firefox.html
Out-of-process plug-ins was made mandatory on Windows Vista and later because Adobe don't test Flash Player's protected mode with OOPP disabled. This change didn't happen until Firefox 14, so there was no need to go as far back as Firefox 9.0.1.
If you absolutely have to, you can disable OOPP by creating the ''MOZ_DISABLE_OOP_PLUGINS'' environment variable and setting its value to '''1'''. Firefox must be restarted for the change to take effect. This works in the current version of Firefox, so there's no need to use obsolete insecure versions.<br>
If you don't know how to create an environment variable, see the following article for instructions (the "Using the Custom Environment Variable" section is not relevant).
* [http://www.howtogeek.com/51807/how-to-create-and-use-global-system-environment-variables/ How to Use Global System Environment Variables | How-To Geek]