What is this "Ubuntu Firefox Modifications" addon in FF 3.5.4 in Karmic

Solution 1:

In this post on an Ubuntu forum thread someone poked around the package contents to see what the addon's source actually does when enabled. It lists the following functions:

1. Enables usage of Ubuntu plugin finder service.
2. Allows localization of extension descriptions.
3. Sets several browser defaults, like printing, look-and-feel, disables checking for default browser, locale matching with OS, etc.
4. Adds Ask.com search plugin.

One undesirable side effect is that it seems to interact oddly with a number of other extensions¹ such that you can not add their toolbar buttons to any toolbars, even on the default theme². Disabling the Ubuntu extension re-enables adding these buttons to toolbars.

Footnotes:
1. most notably FlashBlock and TabMixPlus in my case
2. some people suggest the problem is related to theme choice, I have found this not to be the case

Solution 2:

It allows you to install Firefox add-ons through the Ubuntu package manager. If you disable it, you won't be able to install add-ons through the package manager. You should be able to remove it as normal, but I'd recommend just disabling it at most.

Solution 3:

That extension has been part of Ubuntu's Firefox for a while, or so I thought. I've seen it as early as intrepid. As others have said, it's simply to allow extensions to come in through the Ubuntu repos.

Disabling it will have no ill effects on your system.

To remove it, remove the ubufox package.

Solution 4:

Disabling it also brings back the "middle click paste to go to website in pastebuffer" function. I missed it enormously.