On 18 Oct 2018, at 7:06, じょいすじょん wrote:

That tabbing mechanism is available system wide, provided by AppKit.
It might not be ideal to everybody but it is at least consistent.
Sometimes it's easier to just roll with it and adopt.

It’s actually not a UI component that can be freely used, but rather tabs is something the system can add to document-based applications.

I think there are still too many issues with Cocoa’s document-based application structure for us to adopt it, so the custom tabs will stay for the foreseeable future, which means we can keep the current look where it bleeds into the title bar, although there is something to be said for system-wide consistency.

I agree though that active tab shouldn’t be a button; ideally it would melt together with the document view (as TextMate 1.x did and Chrome currently does).