we have a minor problem in our forum. Some users report a problem with FireFox 44.0 =>Ctrl + left mouse click switches the browser in the new tab instead of opening it in the background.
One user traces the problem back to xenforo.js. He says, there seems to be an error, because a ctrl flag is deleted and a normal click is executed instead of a ctrl click. But the problem seems to appear only in Firefox, not in Chrome or IE.