The following example painted with bad artifacts with 1.6
works fine with 1.5

tested on Windows XP

import javax.swing.*;
import java.awt.*;

public class PaintTest extends JPanel {
    private JComponent view;

    public PaintTest(JComponent view) {
        this.view = view;
        view.setBorder(BorderFactory.createLineBorder(Color.red, 2));
        add(view);
    }

    protected void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        view.paint(g2);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("PaintTest test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        PaintTest t = new PaintTest(new JPanel() {
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.GREEN);
                g.fillRect(0, 0, getWidth(), getHeight());
            }

            public Dimension getPreferredSize() {
                return new Dimension(50, 50);
            }
        });
        frame.add(t);
        frame.setSize(200, 200);
        frame.setVisible(true);
    }
}