One quirk that I discovered in Safari was that new links (the links that are assigned a target=”_blank” attribute) are always opened in a new Safari window, even though you may have set the option to open all links in a new tab in Safari’s preferences.
The fix for this turns out to be simple, as I found out from this blog post. Simply open up Terminal by going to Applications > Uitlities > Terminal.
In the Terminal window that opens, just copy and paste this line of code in and hit enter.
defaults write com.apple.Safari TargetedClicksCreateTabs -bool true
And that’s it! All links will open in a new tab instead of a new window. If you want to reverse this change, you’ll just need to follow the same steps, but using this line of code instead (basically changing “true” to “false” at the end of the line):
defaults write com.apple.Safari TargetedClicksCreateTabs -bool false