Are you a browser fiend? The sort of person who loves Safari, yet can't quite live with some of its peculiarities? If you hadn't guessed, I certainly am one of those people. I love the speed and simplicity of Safari, but it never worked as well as (say) Camino, particularly when it came to persuading links from the likes of Gmail to open in the same window. No number of SIMBL hacks (yes, hacks) seemed to persuade Safari to open links in the existing window - driving me away from Safari, and instead swear by Camino.But that's about to change, as Apple has added a hidden preference to Safari 3.1 that allows you to tell Safari to stick to one window. Even in Gmail. Tipster Dennis Stevense, explains in a blog post that through a simple Terminal command, true one-window mode is finally, finally, here for Safari. All you need to enter is the command below into Terminal, hit enter, and you're sorted.
defaults write com.apple.Safari TargetedClicksCreateTabs -bool true
Thanks Dennis!
Update: If you want to reverse the change, it's a simple matter of entering the following into Terminal:
defaults write com.apple.Safari TargetedClicksCreateTabs -bool false
Thanks to 
