[PLUG] Firefox update broke tab settings

[John Jason Jordan]

I had Firefox preferences set to always open links in a new tab and to
shift focus to the new tab, and it has been working fine for years. This
morning there was an update to Firefox 17.0.1 which broke this setting.
When I click on a link on a page it still opens the link in a new tab
and shifts the focus to the new tab, but it also opens the link in the
original tab, giving me two tabs with the same content. Then I have to
go back to the original tab and hit the back arrow to get the original
page to reload. This happens with all links on all web pages, even
Google search results pages. It's driving me mad.

I've searched everywhere in Preferences and I can't find any way to
change the behavior back to what it was. Unfortunately, the answer may
be there but I just can't find it. There are hundreds of settings and
the possible permutations are an unfathomably large number.

Has this happened to anyone else? Is there a solution?