Something I found on the net today. How to tame the unpredictable (at least to me) behavior of Safari tabs. Sometimes the link will open in new window, sometime it will open in the new tab. How is this determined? Who knows. Here is what I found – to prevent opening links in new window just type this in your terminal -

defaults write com.apple.Safari TargetedClicksCreateTabs -bool TRUE

Et voilà no more issues with new windows.
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Without wax,
yOOrek