Here are the few steps that you need to do this:
- Start Firefox.
- In the Address Bar type about:config and press Enter.
- Find the option that is named browser.link.open_newwindow.restriction and double-click on it.
- Restart Firefox.
This is probably one of my favorite “about:config” tweaks that I have done. I use tabs for a reason and that is because I don’t want to have windows open all over the place. I’m pretty sure that the Tab Mix Plus extension covers this feature but ever since Firefox 2 I haven’t really felt the need to install it.