"Tab bar" in View menu on macOS Sierra
In 2.1 release and 2.2 nightly 3f4efd8, on macOS 10.12 Sierra (and probably also 10.13 High Sierra), the option "Show/Hide Tab Bar" appears at the top of the View menu. This is a new feature in macOS that allows programs that open documents in separate windows (which is something I'd like in MuseScore, but that's another topic) to combine them into a single tabbed window, but since MuseScore already uses a single tabbed window with its own row of tabs, we should prevent this extra menu command from being added.
"What should an application which already has support for tabbing do? - The application should explicitly opt-out of automatic window tabbing by calling [NSWindow setAllowsAutomaticWindowTabbing:NO]."