For some time now, Firefox 3.6 has been -- to my annoyance -- recycling tabs when I click links from other applications.
If I click a link in Thunderbird, for instance, it opens in an existing tab in Firefox, opposed to opening a new one. This results in me always having to first switch to Firefox, open a new tab, switch back to the application and click the link.
I have no idea what is causing this behavior. I took a brief look at
about:config, but nothing under
browser.tabs seemed relevant.
This behavior also occurs in Minefield 4.0b3. I have only a handful of addons: AdBlock, Firefox Sync, Locationbar² and Session Manager. I have both Tab Mix Plus and Tab Control installed, but disabled.