Must install Java 6 Update 7 plugin.
We have a web app that is a core component of our business and it will only run with Java 6 Update 7, It has been tested up to Update 17. From what I finding through the forums, helps and other sources it seems the Firefox 19.0 will not allow this plugin to be installed. I can work with this mess related to allowing one website access to the Plugin, but if Firefox can block the install of the product I would hope that there is some method to over-ride the hard coded language that does not allow java 6 installs if they are older than Update 31.
I would simply switch browsers but there are other considerations that makes the browser swap a bit problematic.
Alle svar (1)
Old Java is not safe on untrusted or compromised sites, so you should be cautious about using it on the wilds of the web. You might consider creating two parallel instances of Firefox, one for your app (with old Java) and another for regular browsing (with newer Java or no Java) in order to limit your vulnerability.
That said, for your "vulnerable" profile, note that Firefox uses a data file to identify unsafe add-ons. By default, a new blocklist.xml is downloaded every 24 hours. This article has more info on the file and related settings: http://kb.mozillazine.org/Blocklist.xml. For anyone disabling the blocklist, it becomes more important to take manual action to root out old other insecure plugins manually. The Plugin Check site can help with that.
Regarding running multiple Firefox instances/profiles in parallel, see, for example, Two Firefox at the same time, (one with images, other without)?