question: public void addButton ( URL url , String info , ActionListener al ) { JButton b = new JButton ( new ImageIcon ( url , info ) ) ; b . setToolTipText ( info ) ; b . setMargin ( new Insets ( 0 , 0 , 0 , 0 ) ) ; b . addActionListener ( al ) ; b . setBorderPainted ( false ) ; add ( b ) ; }
target:  Add a button to the panel.