It's very easy to get a client-decorated JFrame to dance around the edges of the screen. This behavior is obviously very wrong.

To reproduce:

Run the included test (PopupMenuDemo.java). The .gif isn't required to reproduce.

Click on the title bar and in one continuous motion move the
window to the center of the screen and move it in a small circle
around the center of the screen. The window will dance all over the screen.

Also, sometimes when the mouse button is released on the title bar after
moving the window, the window maximizes, as if there was a doubleclick.

This is reproducible w/ XAWT on RedHat 9 w/ the stock metacity (2.4.34) as well as the later metacity 2.6.2. b29 exhibits this behavior, and probably several builds back.

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import java.awt.*;
import java.awt.event.*;
import javax.swing.JPopupMenu;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.ButtonGroup;
import javax.swing.JMenuBar;
import javax.swing.KeyStroke;
import javax.swing.ImageIcon;

import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JFrame;

/* PopupMenuDemo.java is a 1.4 application that requires images/middle.gif. */

/*
 * Like MenuDemo, but with popup menus added.
 */
public class PopupMenuDemo implements ActionListener, ItemListener {
    JTextArea output;
    JScrollPane scrollPane;
    String newline = "\n";

    public JMenuBar createMenuBar() {
        JMenuBar menuBar;
        JMenu menu, submenu;
        JMenuItem menuItem;
        JRadioButtonMenuItem rbMenuItem;
        JCheckBoxMenuItem cbMenuItem;

        //Create the menu bar.
        menuBar = new JMenuBar();

        //Build the first menu.
        menu = new JMenu("A Menu");
        menu.setMnemonic(KeyEvent.VK_A);
        menu.getAccessibleContext().setAccessibleDescription(
                "The only menu in this program that has menu items");
        menuBar.add(menu);

        //a group of JMenuItems
        menuItem = new JMenuItem("A text-only menu item",
                                 KeyEvent.VK_T);
        //menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead
        menuItem.setAccelerator(KeyStroke.getKeyStroke(
                KeyEvent.VK_1, ActionEvent.ALT_MASK));
        menuItem.getAccessibleContext().setAccessibleDescription(
                "This doesn't really do anything");
        menuItem.addActionListener(this);
        menu.add(menuItem);

        ImageIcon icon = createImageIcon("images/middle.gif");
        menuItem = new JMenuItem("Both text and icon", icon);
        menuItem.setMnemonic(KeyEvent.VK_B);
        menuItem.addActionListener(this);
        menu.add(menuItem);

        menuItem = new JMenuItem(icon);
        menuItem.setMnemonic(KeyEvent.VK_D);
        menuItem.addActionListener(this);
        menu.add(menuItem);

        //a group of radio button menu items
        menu.addSeparator();
        ButtonGroup group = new ButtonGroup();

        rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
        rbMenuItem.setSelected(true);
        rbMenuItem.setMnemonic(KeyEvent.VK_R);
        group.add(rbMenuItem);
        rbMenuItem.addActionListener(this);
        menu.add(rbMenuItem);

        rbMenuItem = new JRadioButtonMenuItem("Another one");
        rbMenuItem.setMnemonic(KeyEvent.VK_O);
        group.add(rbMenuItem);
        rbMenuItem.addActionListener(this);
        menu.add(rbMenuItem);

        //a group of check box menu items
        menu.addSeparator();
        cbMenuItem = new JCheckBoxMenuItem("A check box menu item");
        cbMenuItem.setMnemonic(KeyEvent.VK_C);
        cbMenuItem.addItemListener(this);
        menu.add(cbMenuItem);

        cbMenuItem = new JCheckBoxMenuItem("Another one");
        cbMenuItem.setMnemonic(KeyEvent.VK_H);
        cbMenuItem.addItemListener(this);
        menu.add(cbMenuItem);

        //a submenu
        menu.addSeparator();
        submenu = new JMenu("A submenu");
        submenu.setMnemonic(KeyEvent.VK_S);

        menuItem = new JMenuItem("An item in the submenu");
        menuItem.setAccelerator(KeyStroke.getKeyStroke(
                KeyEvent.VK_2, ActionEvent.ALT_MASK));
        menuItem.addActionListener(this);
        submenu.add(menuItem);

        menuItem = new JMenuItem("Another item");
        menuItem.addActionListener(this);
        submenu.add(menuItem);
        menu.add(submenu);

        //Build second menu in the menu bar.
        menu = new JMenu("Another Menu");
        menu.setMnemonic(KeyEvent.VK_N);
        menu.getAccessibleContext().setAccessibleDescription(
                "This menu does nothing");
        menuBar.add(menu);

        return menuBar;
    }

    public Container createContentPane() {
        //Create the content-pane-to-be.
        JPanel contentPane = new JPanel(new BorderLayout());
        contentPane.setOpaque(true);

        //Create a scrolled text area.
        output = new JTextArea(5, 30);
        output.setEditable(false);
        scrollPane = new JScrollPane(output);

        //Add the text area to the content pane.
        contentPane.add(scrollPane, BorderLayout.CENTER);

        return contentPane;
    }

    public void createPopupMenu() {
        JMenuItem menuItem;

        //Create the popup menu.
        JPopupMenu popup = new JPopupMenu();
        menuItem = new JMenuItem("A popup menu item");
        menuItem.addActionListener(this);
        popup.add(menuItem);
        menuItem = new JMenuItem("Another popup menu item");
        menuItem.addActionListener(this);
        popup.add(menuItem);

        //Add listener to the text area so the popup menu can come up.
        MouseListener popupListener = new PopupListener(popup);
        output.addMouseListener(popupListener);
    }

    public void actionPerformed(ActionEvent e) {
        JMenuItem source = (JMenuItem)(e.getSource());
        String s = "Action event detected."
                   + newline
                   + " Event source: " + source.getText()
                   + " (an instance of " + getClassName(source) + ")";
        output.append(s + newline);
    }

    public void itemStateChanged(ItemEvent e) {
        JMenuItem source = (JMenuItem)(e.getSource());
        String s = "Item event detected."
                   + newline
                   + " Event source: " + source.getText()
                   + " (an instance of " + getClassName(source) + ")"
                   + newline
                   + " New state: "
                   + ((e.getStateChange() == ItemEvent.SELECTED) ?
                     "selected":"unselected");
        output.append(s + newline);
    }

    // Returns just the class name -- no package info.
    protected String getClassName(Object o) {
        String classString = o.getClass().getName();
        int dotIndex = classString.lastIndexOf(".");
        return classString.substring(dotIndex+1);
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = PopupMenuDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    public static void main(String[] args) {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("PopupMenuDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create/set menu bar and content pane.
        PopupMenuDemo demo = new PopupMenuDemo();
        frame.setJMenuBar(demo.createMenuBar());
        frame.setContentPane(demo.createContentPane());

        //Create and set up the popup menu.
        demo.createPopupMenu();

        //Display the window.
        frame.setSize(450, 260);
        frame.setVisible(true);
    }

    class PopupListener extends MouseAdapter {
        JPopupMenu popup;

        PopupListener(JPopupMenu popupMenu) {
            popup = popupMenu;
        }

        public void mousePressed(MouseEvent e) {
            maybeShowPopup(e);
        }

        public void mouseReleased(MouseEvent e) {
            maybeShowPopup(e);
        }

        private void maybeShowPopup(MouseEvent e) {
            if (e.isPopupTrigger()) {
                popup.show(e.getComponent(),
                           e.getX(), e.getY());
            }
        }
    }
}