The enclosed application has a frame with a menu bar which has
a help menu. The help menu has an About entry which pops up
a standard dialog containing strings previously given.

Almost.

It flashes up the dialog, but it disappears immediately,
leaving a brief afterflow on the screen :-)

Surprisingly, if I add in a printstatment between the calls of
pack() and show() for the dialog, it displays correctly.

There is a print statement in the code that prints "delay" ...
try running the program with and without the comment characters.



import java.awt.Dialog;
import java.awt.Dimension;
import java.awt.Event;
import java.awt.Frame;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Label;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.MenuItem;
import java.awt.Panel;
import java.awt.Rectangle;

public class Main extends Frame
{
    public static void main(String[] args) {
Main m = new Main();
m.show();
    }

    Main() {
super("DEMO");

add("Center", new Label("DEMO"));

MenuBar mb = new MenuBar();
Menu helpMenu = new Menu("Help");
helpMenu.add(new HelpAbout(this, "About", "DEMO", aboutInfo));
mb.add(helpMenu);
mb.setHelpMenu(helpMenu);
setMenuBar(mb);

pack();
    }


    static String[] aboutInfo = {
        "DEMO",
        "Jonathan Gibbons",
        "Copyright (C) 1996 Sun Microsystems, Inc."
    };
}

/**
 * HelpAbout is a MenuItem that displays an array of strings when activated.
 * It is intended to simpify the provision of an About... entry on a Help menu.
 *
 * @author Jonathan J Gibbons
 * @version %I% %G%
 */

class HelpAbout extends MenuItem
{
    public HelpAbout(Frame parent, String name, String dialogName, String[] info) {
super(name);
this.parent = parent;
this.dialogName = dialogName;
this.info = info;
    }

    public boolean postEvent(Event evt) {
if (evt.id == Event.ACTION_EVENT && evt.target == this) {
Dialog d = new HelpAboutDialog(parent, dialogName, info);
Dimension s = d.size();
Rectangle b = parent.bounds();
d.move(b.x + (b.width - s.width)/2, b.y + (b.height - s.height)/2);
    //System.out.println("delay");
d.show();
return true;
}
return false;
    }

    private Frame parent;
    private String dialogName;
    private String[] info;
}


class HelpAboutDialog extends Dialog
{
    HelpAboutDialog(Frame parent, String name, String[] info) {
super(parent, name, false);
setResizable(false);

Panel p = new Panel();
GridBagLayout gbl = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
p.setLayout(gbl);
c.gridwidth = GridBagConstraints.REMAINDER;
c.anchor = GridBagConstraints.CENTER;
c.insets.top = c.insets.bottom = c.insets.left = c.insets.right = 10;

for (int i = 0; i < info.length; i++) {
Label l = new Label(info[i]);
gbl.setConstraints(l, c);
p.add(l);
}

add ("Center", p);

pack();
    }

    public boolean handleEvent(Event evt) {
if (evt.id == Event.WINDOW_DESTROY && evt.target == this) {
dispose();
return true;
}

return false;
    }
}