elementary OS has one, which is well-enforced in their first-party and many third-party apps: https://elementary.io/docs/human-interface-guidelines https://elem

elementary OS has one, which is well-enforced in their first-party and many third-party apps: https://elementary.io/docs/human-interface-guidelines https://elementary.io/docs/human-interface-guidelines Of course, as soon as you go outside that, you run into the fragmentation prevalent in the Linux desktop. For light computer users or people who can get by without a bunch of specialized graphical apps, it works well and is very intuitive.