The following exception is thrown as result of FileDialog.setVisible(true) call

Exception in thread "main" java.lang.NullPointerException: null pData
       at sun.awt.windows.WWindowPeer.setFocusableWindow(Native Method)
       at sun.awt.windows.WWindowPeer.updateFocusableWindowState(WWindowPeer.java:66)
       at java.awt.Window.updateChildFocusableWindowState(Window.java:753)
       at java.awt.Dialog.conditionalShow(Dialog.java:928)
       at java.awt.Dialog.show(Dialog.java:1032)
       at java.awt.Component.show(Component.java:1415)
       at java.awt.Component.setVisible(Component.java:1368)
       at java.awt.Window.setVisible(Window.java:694)
       at java.awt.Dialog.setVisible(Dialog.java:983)
       at test.main(test.java:13)

It's a regression of the fix for the bug (fixed in b79):
6391763 REG: Window not gaining focus even after the parent dialog is made visible, WinXP

This code (see Dialog.java) makes the bug visible:
925 Window.updateChildFocusableWindowState(this);

here's simple test to reproduce the problem.
=================
import java.awt.*;
import java.awt.event.*;

public class test {


    final static Frame frame = new Frame("frame");
    public static void main(String[] argv){

FileDialog fd = new FileDialog(frame);
fd.setMode(FileDialog.LOAD);
fd.setTitle("File dialog");
fd.setVisible(true);
    }

}