Marking/closing questions as a duplicate is a delicate subject, and there is a thin line between whether a post is a duplicate or not.

 [This one][1] however hurts my eyes. While OP ctearly mentions he wants to close *the latest opened window (instance)* of Firefox, the question was closed as a duplicate of a question about *closing a tab* of Firefox. Quite different. I even explained it in the comment.
Interesting detail is that the first one to mark as a duplicate also answered the question afterwards.

Moreover, the duplicate does not offer a solution sideways as well. 

Can this be undone?


  [1]: http://askubuntu.com/questions/616738/how-to-close-a-new-firefox-window-from-terminalcfct-command-is-not-working/616767#616767