Nowadays, Mathematica highlights per default the enclosed function you are in by colouring the braces as well as the head. Unfortunately, since version 11.0 this seems to have a font problem. What happens is that the green background highlighting slightly changes the width of the font (at least it seems so). When you now browse through your code and the enclosing function changes because you move the cursor inside a different function, several lines are slightly shifted. Let me give an example where you need to pay attention how several lines wiggle when I move the cursor:
This might be a minor annoyance but believe me, it drives you crazy when you edit a large portion of code. I tried to fix it by changing the style of the highlighting but I had no success. I reset Mathematica with mathematica -cleanstart
but that didn't change a thing.
It is probably my own fault since I didn't report it in the pre-release but this issue seemed so obvious to me that I thought it will definitely be fixed in the release. Now, we already have 11.1.1 out and the bug still persists. Is it only me or do other Linux users have the same problem?
I'm on XUbuntu 16.04 with the latest Mathematica. Any thoughts?
Edit
I have filed a bug-report [CASE:3884553]