The sample Intuition program that follows shows all of the basic
requirements for an Intuition application. There are three important
points:

  * You must open the Intuition library before you can use the Intuition
    functions.  Certain languages such as  require the pointer to the
    Intuition library to be assigned to a variable called IntuitionBase
    (see chapter 1 for more about this).

  * When you set up a window, you also specify the events that you want
    to know about.  If the user performs some activity that triggers one
    of the events you specified, Intuition signals you and sends a
    message.  the message is a pointer to an intuimessage data structure
    that describes the event in more detail.  Messages about Intuition
    events are sent to a msgport structure which queues up the messages
    for you in a linked list so that you may respond to them at your
    convenience.

  * Resources must be returned to the system.  in this case, any windows,
    screens or libraries that were opened are closed before exiting.

 example intuition event loop 
 intuition example (v36 and later) 
 intuition example (all versions)