by a resize of a applet with the mouse ,the paint method is called several times

import java.applet.*;
import java.awt.*;

public class PaintTest extends Applet {
    protected PanelObject panel;
    protected int counter;
    public PaintTest() {
        panel = new PanelObject();
        setLayout(new BorderLayout());
        add("Center", panel);
        add("South", new Button("button1"));
    }
    public void paint(Graphics g) {
        System.out.println("paint parent" + "counter" + counter);
        counter++;
    }
    public boolean action(Event evt, Object arg) {
        System.out.println("action");
        repaint();
        return true;
    }
}

class PanelObject extends Panel {
    protected int counter;
    PanelObject() {
    }
    
    public void paint(Graphics g) {
        System.out.println("paint child" + " counter" + counter);
        counter++;
    }
}


> appletviewer update.html
status: applet loaded
status: applet initialized
status: applet started
paint child counter0


// when I do the first resize with the mouse I got this printout.
paint child counter1
paint parentcounter0
paint parentcounter1
paint child counter2
paint parentcounter2
paint parentcounter3
paint parentcounter4
paint child counter3

I think it's not a correct output, the paint method should be called only once.