How to reproduce:

1) compile SetBar.java

  import java.awt.*;
  import java.awt.event.*;
  public class SetBar extends Frame{
    SetBar() {
        setSize(200,200);
        addMouseListener( new MouseAdapter() {
           public void mouseClicked(MouseEvent e){
              setMenuBar();
           }});
        show();
    }
    void setMenuBar(){
        MenuBar bar = new MenuBar();
        bar.add(new Menu("first menu"));
        setMenuBar(bar);
    }
    public static void main(String argv[]){
     new SetBar();
    }
  }

2) run SetBar.class

3) click the center of it's frame pane and then the frame moves
against user's will.

This phenomenon happens only when you click it for the first time.
If you click on it at the second time after 1st movement, the frame
keeps its position.

Tested Environment:
Solaris 2.6 on SPARC and Solaris 2.6 on Intel
iwabuchi@dandelion> java -fullversion
java full version "JDK1.1.8H"

I can't see this bug on WindowsNT4.0.