That's a really annoying one.

List of steps to reproduce:

• Open any wiki page with interwikis.
• Click the number of languages.
  
• Move the cursor to the left (or upper, or lower, or right) border of the highlighted area of any language in the list.
  
• Ctrl+click to open the page in another language in a new tab.

What happens?:
A new tab doesn't open. The page loads in the same tab.

What should have happened instead?:
A new tab should open.

Explanation:
The reason for this is that the highlighted area is not equal to the link area. A LI item is highlighted instead of A.

A is inside the blue area here, while the green area (LI's padding) is highlighted too. Right click on the green area doesn't work for the link as well, obviously.

Suggestion:
To enlarge the link area to the borders of LI, and to make it responsible for highlighting instead of LI to remove the discrepancy between what area is relevant and what area is highlighted.