I middle click coordinate links a lot on Wikipedia articles to open them in a new background tab. Today I noticed that it doesn't work properly in some Wikipedias (e.g. English, German), instead it reacts like a left click and loads in the current tab. It works fine in other Wikipedias (e.g. French, Spanish).
e.g. Try to middle click the coordinates in the top right on https://en.wikipedia.org/wiki/Berlin and it loads in the same tab. Do the same on https://fr.wikipedia.org/wiki/Berlin and it opens a new tab.
It only seems to affect WebKit/Blink-based browsers (both old and new). It works as expected for me in Firefox 37, Firefox 24 and Opera 12, but not in Chromium 43, Chromium 33, Safari 5.1 or Vivaldi TP4.
I have no idea which projects this belongs under, sorry, but since it's happening on multiple sites I presume it's not something the local wikis did and have therefore reported it here. :)