src/vs/base/browser/ui/menu/menubar.ts/MenuBar/toggleFocus
class MenuBar:	toggleFocus(): void {
		if (!this.isFocused && this.options.visibility !== 'hidden') {
			this.mnemonicsInUse = true;
			this.focusedMenu = { index: this.numMenusShown > 0 ? 0 : MenuBar.OVERFLOW_INDEX };
			this.focusState = MenubarState.FOCUSED;
		} else if (!this.isOpen) {
			this.setUnfocusedState();
		}
	}