I found this with an internet search. I could find nothing like this within Opera itself. I must have missed it.
Go to the address bar and enter: "opera://flags" (without quotes)
That will take you to a long list of options, one of which is to enable smooth scrolling.
Why smooth scrolling is not enabled out of the box and why it is hidden in opera://flags (which doesn't seem to be announced anywhere obvious) is a complete mystery.
@1outlaw3 This is a longstanding issue created by Opera's developers. They refuse to address the problem. There are workarounds. Some of these workarounds might help users of Manjaro running XFCE.
Hi @mr-xecute, you can run the Opera with "--disable-update" command line switch, also you can rename the "opera_autoupdate" file to not be launched at all - you can find the path to it in opera:about > Paths > Install.
@aintab Oh, nailed it. Found opera-developer's apt package and installed it.
Then I ran command chmod 777 for opera-developer folder and paste the libffmpeg.so file. It worked.