Add buttons to Mac window Title Bars, system-wide

Question

I want to be able to add a button to the title bar of all windows that open on a Mac.

The button will go on the right hand side, opposite the X -

Answer 1

Swift 4 - In NSWindowController add the below code

if let window = window {
    let myButton = NSButton()
    myButton.title = "Help"
    myButton.bezelStyle = .rounded

    let titleBarView = window.standardWindowButton(.closeButton)!.superview!
    titleBarView.addSubview(myButton)
    myButton.translatesAutoresizingMaskIntoConstraints = false
    titleBarView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[myButton]-2-|", options: [], metrics: nil, views: ["myButton": myButton]))
    titleBarView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-1-[myButton]-3-|", options: [], metrics: nil, views: ["myButton": myButton]))
}

Hope this is helpful.