UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/68.0.3440.75 Chrome/68.0.3440.75 Safari/537.36

Steps to reproduce the problem:
1. Go to any page that doesn't fit on the scren at once. Chromium bugs list works. 
2. scroll down a bit.
3. middle click on the scrollbar on the right. 

What is the expected behavior?
I'm used to having the visible window on the document jump so that the top of the "visible part" aligns with my mouse click. For example, in a long document middle click near the top to jump to the top. 

What went wrong?
The visible window no longer moves. 

leftclick in the scrollbar area scrolls towards here (up when you're above the visible part, down when you click below). That still works (but I normally don't use it: It seems I didn't know correctly what it did before researching that I wasn't saying nonsense. I was. :-) ) 

Did this work before? Yes On ubuntu: A couple of months ago. (I was hoping it would get fixed without my reporting it). 

Chrome version: 68.0.3440.75  Channel: n/a
OS Version: Ubuntu 18.04
Flash Version: dontknow

It's annoying. I use it a lot and my brain can't adjust to it no longer working. :-)