title: How to assign a function the mousedown event of an NSButton in Cocoa without subclassing?
body: <p>I'm trying to find a way to get notified of all NSResponder "events", but without having to subclass the NSControl I'm interested in. For example, I would like to get notified about mouse events from NSButton without having to subclass it. I know there is a way specific for mouse events, but I'm interested in all events provided by NSResponder, including Key events.</p>
  
  <p>Is there a way to do it, like in C# or Delphi where you attach a function to an event?</p>
  
  <p>Edit: I would like to do it at runtime.</p>
  
  <p>Regards</p>