Hi, which software / codebase is this about? (Isn't this a local web browser or desktop environment setting?)

It can be done with CSS

html {
  scroll-behavior: smooth;
}

In which software stack? MediaWiki?

Sorry, I don't understand your question. This is something that can be solved with CSS, and could be added to common.css, as mentioned in the feature request.

Where to see non-smooth scrolling?

Non-smooth is the current one.

I know. Where? A MediaWiki page? Some other software?

It feels quite weird to ask questions that are described in the feature request themselves. I don't know what the purpose of asking again and again the same thing is: just making volunteers lose their time? Shaming them for not describing things exactly as you would like? Making requests more painful?

The feature is requested. Take it as it is.

@Theklan: Phabricator is used for many software projects. By now I guess that you mean MediaWiki. I do not understand either volunteers repeatedly avoiding to answer a pretty simple question to make other people (in this case staff, though that really does not matter) lose their time.

I don't know what the purpose of asking again and again the same thing is: just making volunteers lose their time?

@Theklan no, it is to get AS MUCH relevant, accurate and required information as possible UP FRONT, so that developers have to spend less time questioning people. If I have a link, I can take a look, if I have to ASK for a link, I'm spending time and have to change focus, or I have to go on an information hunt in an area where I might not be as familiar as the reporter. Both are highly inefficient.

There are 300 software projects being tracked here, close to a thousand wikis of 8 different types in 340 languages, using 50+ extensions, 20 different content types, 6 skins, mobile vs desktop, 4 different browsers, hundreds of gadgets etc etc etc. As a developer I need all the help I can get to make sure I'm looking in the right place and analysing the right problem.