Simple solution for those who don't want to do it through "about:config". Otherwise do as stated :
by moziloper, 2 years ago I think this extension only simplifies the manual inclusion of this option: "browser.tabs.insertAfterCurrent"
This can be done manually using two steps: 1. Type in the address bar: "about:config?filter=browser.tabs.insertAfterCurrent". 2. Set to "true" by double click on it.
