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

This answer addresses the latest Xcode Version 9.3

• Go to a storyboard.
• Drag and drop a toolbar in the storyboard to a Window.

• The toolbar will be visible below a title.

• Locate the Window on the storyboard

• Check "Hide Title" in properties of the Window.

• The toolbar is a part of the title now.