Listing 2. Instantiate GUI components.
  Panel mainPanel = new Panel();
  
  Label angleLabel = new Label("Enter Angle");
  TextField angleField = new TextField("000");
  
  Label distanceLabel = new Label("Enter Distance");
  TextField distanceField = new TextField("000");
  
  Button moveButton = new Button("Move");
  Button quitButton = new Button("Quit");
  
  int angle = 0;
  int distance = 0;