Jan Holthuis

Rebased on #4673 to make stuff like `SelectTrackKnob` work.

Rebased, ready to review again.

@uklotzde > With a fresh profile the library panel remains empty. What do you mean by "it remains empty"? Is this a regression from the current QML library?

> @uklotzde > > > With a fresh profile the library panel remains empty. > > What do you mean by "it remains empty"? Is this a regression from the...

I'd prefer if this file was maintained outside the Mixxx repo. Maybe the [nixpkgs repo](https://github.com/NixOS/nixpkgs) would be willing to add an additional `mixxx-git` package that provides the latest dev version...

> Nix is a isolated, self containing build system/package system that can run on any unix like system. Sure, if you think that distro independence of the nix package is...

I only had a superfluous look, but at least the naming conflicts with: https://github.com/mixxxdj/mixxx/pull/2989 **EDIT:** You were quicker already edited a paragraph into your PR description :D The actual functionality...

> "Quick Actions" in Deperados I think the name "Quick Action" would fit well here, too.

CI builds are failing btw.

> This means removing the packaging and only keep the environment setup stuff? There's probably a way to install dependencies for the mentioned `default.nix` file. For example, if you want...