import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class UndoButton extends JButton {
private MainPanel _m;
public UndoButton(MainPanel m) {
super("Undo");
_m = m;
addActionListener(new UndoButtonListener());
}
class UndoButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// System.out.println("Undo button pressed!");
_m.undo();
}
}
}