This applet illustrates (again) the use of paint to draw something
(in this case, some text) on the applet.
- paint must be included in every applet that does some drawing (graphics).
- paint is never called by the program directly. Instead, the program must invoke
repaint() whenever the need for redrawing something on the screen appears.
- The exercises combine paint with a button click to redraw (repaint) something new on the screen
each time the button is pressed.