hanging the button title. The normal memory-management
    policy in Cocoa is that if we allocate an object (like the
    NSString "Hello!") we are responsible for releasing it. Unlike
    Lisp, Cocoa does not automatically garbage-collect all allocated
    objects by default.</p>

    <p>Giving the button an action is slightly more
    complicated. Clicking a button causes the button object to send a
    message to a target object. We haven't given our button a message
    to send, nor a target object to s