After the buttons have been displayed by displayButtons, that method sets the looking for mechanism to look for a single character input, and to invoke the method pushButton when the character is received.
The pushButton method takes one character of input from the user, figures out which button is intended
(if any), sends out the remainder of the button name, and then sends a mouseUp message to the selected button. Usually, the mouseUp causes a jump to another card, starting the whole process over again from the beginning.