Create a Java program which contains a Frame with a Menubar. Set up
the Java program to monitor some non-user events (such as: a file
exceeding a certain file size) and pop up a modal dialog when the
event occurs.

If the dialog appears when a menu bar menu is displayed, the system
may lock up. The customer was able to produce the lock-up when the
        dialog contained a button whose role was to dispose of the modal dialog.
Without the button, the customer got no lock-up.

Here is a test case which reproduces the problem. It includes two
files: "Makefile" and "Main.java". To build it, run 'make build'. To
run it, run 'make run'.

When the Frame appears, bring up the File menu and leave it up. In a
few seconds, the modal dialog will appear; push the OK button and your
system will be locked up. To unlock, be prepared to log in to another
workstation and kill the JVM process running the test case.
 
TEST CASE
---------

------------------------------ Makefile ------------------------------

JAVA_HOME = /usr/java
CLASSPATH = .:$(JAVA_HOME)/lib/classes.zip

JAVAC = $(JAVA_HOME)/bin/javac -classpath $(CLASSPATH)
JAVA = $(JAVA_HOME)/bin/java
JAR = $(JAVA_HOME)/bin/jar
RM = /usr/bin/rm -f

build:
$(JAVAC) LockUp.java

run:
@JAVA_HOME=$(JAVA_HOME); export JAVA_HOME; CLASSPATH=$(CLASSPATH); export CLASSPATH; $(JAVA) LockUp

clean:
$(RM) *.class

---------------------------- Lockup.java ----------------------------

import java.awt.*;
import java.awt.event.*;

class LockUp
{

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

LockUp()
{
Frame frame = new Frame();

MenuBar menuBar = new MenuBar();
frame.setMenuBar(menuBar);

Menu file = new Menu("File");
menuBar.add(file);

MenuItem menuItem = new MenuItem("A Menu Entry");
file.add(menuItem);

frame.setSize(600, 400);
frame.setVisible(true);

// Allow time to pop up the menu

try {
Thread.currentThread().sleep(5000);
}
catch (InterruptedException exception) {
}

dialog = new Dialog(frame);

Button button = new Button ("Close");
dialog.add(button);
button.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e)
{ dialog.dispose(); } }
);


dialog.setSize(200, 200);
dialog.setModal(true);
dialog.setVisible(true);

System.out.println("No lock-up occurred");
System.exit(0);
}

private Dialog dialog;

}