Ubuntu really has no control over what Firefox does or does not do with their plug-ins.
Information regarding this plug-in:
About this Add-on
AutoProxy is an add-on to help you use your proxy (http/socks) automatically & efficiently.
With AutoProxy, you no longer need to switch your proxy status between on & off manually. If you prefer to visit a website via proxy, just add it's domain to AutoProxy's preference. After that, when you surfing, specified websites will be transfered through proxy while leaving others connect directly.
What's more, you can subscribe to rule lists maintained by people who have similar requirements as you. So, you don't need to add all proxy rules by yourself.
"gfwList" is a list for people in mainland China suffering from the censorship of GFW. If you aren't in mainland China, please do NOT subscribe to "gfwList". AutoProxy should contain lists for other requirements. If you'd like to share your proxy rules to people in the same state/school/company/network...by maintaining a rule list, it would always be most appreciated, please check out http://autoproxy.org/en/subscriptions .
AutoProxy is derived from Adblock Plus, thanks the ABP community especially it's author Wladimir Palant!