Compile and run the following codes under jdk1.3.1, you will find that the new created frame will move automatically, but under jdk1.2 and jdk1.4, the codes work well.

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

public class Test {
    public Test() {
        JFrame f = new JFrame("Test JFrame");
	JPanel p = new JPanel(new FlowLayout());
	JButton btn = new JButton("New Frame");
	btn.addActionListener(new ActionListener() {
	    public void actionPerformed(ActionEvent evt) {
	        JFrame newFrame = new JFrame("popup frame");
		JPanel pp = new JPanel();
		pp.setPreferredSize(new Dimension(300, 400));
		newFrame.setContentPane(pp);
		newFrame.pack();
		newFrame.setVisible(true);
	    }
	});
	p.add(btn);
	f.setContentPane(p);
	f.pack();
	f.setVisible(true);
    }

    public static void main(String[] args) {
        new Test();
    }
}

following is the java version info:

java version "1.3.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24)
Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode)

 xxxxx@xxxxx  2001-06-28
if we add the statement JFrame.setLocation() after pack() and before setVisible(), then the bug disappear.

This will happen if use only awt as well, reassigning to awt.
 xxxxx@xxxxx  2001-06-28

Yes, this is reproducable under 1.3.1, but not 1.4 so marking it as not reproducable under 1.4 as that is the next release.
 xxxxx@xxxxx  2001-06-28