Why does the ALT key disable mouse clicks on some machines?

Question

I have a drawing program, the main Window of which extends JFrame and contains a Canvas, which extends JPanel. The Canvas has a MouseAdapter, KeyAdapter and JMenuBar. It also has a Tools palette, which extends JDialog and has Buttons, which extend JToggleButtons.
One button is called Zoom. After pressing this button, you can Zoom In and Zoom Out by clicking the mouse on a point of the illustration. It differs from pressing Ctrl Plus and Ctrl Minus, because the point where you click is kept in place, and only all the other points move.
Zooming In is done by clicking the mouse and Zooming Out is done by pressing the ALT key and clicking the mouse. The Zooming In works on all computers, but for some strange reason, the Zooming Out doesn't work on all computers. The computer where it doesn't work, after pressing the ALT key and clicking the mouse, it does not recognize the mouse click, and never reaches the mousePressed method in my debugger.
The computer where it doesn't work has the Windows XP Professional operating system. But some computers where it does work have the same operating system. The problem also does not depend on the keyboard or mouse, because I tried a different keyboard and mouse, and it still didn't work.
I wonder if the reason why it doesn't work on some computers has to do with that the ALT key is also used differently (which might depend on the operating system)? Pressing the ALT key and clicking the mouse Zooms In a picture by keeping the point in place and only moving all the other points
I do not want to use a different key, since one release of my program is a plugin for Photoshop, and Photoshop also uses the ALT key to achieve the same thing.
Thanks for checking on this! I will appreciate your help!

Answer 1

Ok, I did apply KeyBindings. Since the AnanyaCurves class extends JFrame, I couldn't apply KeyBindings there, but I could apply KeyBindings to my CurveCanvas class, which extends JPanel, which extends JComponent. However I still have my first two problems:
1) After pressing the ALT key, clicking the mouse doesn't get recognized. You never reach the mousePressed method, where it's supposed to exit the program.
2) After opening a menu, such as the Nothing menu by pressing ALT and N, pressing a key which is not an accelerator key of a menu doesn't get recognized, such as pressing the E key. You never reach the actionPerformed method of the exitF action, where it's supposed to exit the program.
Here is my SSCCE with the KeyBindings:
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.lang.reflect.*;
import java.util.*;
import javax.swing.*;
import javax.swing.plaf.*;
public class AnanyaCurves extends JFrame
  CurveCanvas canvas;
  JMenuBar menuBar;
  Command quitCmd;
  JMenu fileMenu, nothingMenu;
  JMenuItem quitItem, nothingItem;
  boolean alt;
  public AnanyaCurves(Dimension windowSize)
    Font boldFont = new Font("Verdana", Font.BOLD, 12);
    Font plainFont = new Font("Verdana", Font.PLAIN, 12);
    Object top;
    Basics.ananyaCurves = this;
    alt = false;
    try
      UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
      SwingUtilities.updateComponentTreeUI(this);
    catch(Exception e)
    UIManager.put("MenuItem.acceleratorFont", new FontUIResource(UIManager.getFont("MenuItem.acceleratorFont").decode("Verdana-PLAIN-12")));
    Basics.ananyaCurves = this;
    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
    setTitle("Ananya Curves");
    Dimension docSize = new Dimension(274, 121);
    canvas = new CurveCanvas(docSize);   
    menuBar = new JMenuBar();
    setJMenuBar(menuBar);
    fileMenu = new JMenu("File");
    fileMenu.setMnemonic('F');
    fileMenu.setFont(boldFont);
    quitCmd = new Command("quit", "ctrl Q");
    quitCmd.putValue(Action.NAME, "Quit");
    quitItem = new JMenuItem(quitCmd);
    quitItem.setFont(plainFont);
    fileMenu.add(quitItem);
    menuBar.add(fileMenu);
    //fileMenu.setVisible(false);
    /*JMenuBar hiddenMenuBar = new JMenuBar();
    hiddenMenuBar.add(fileMenu);
    getContentPane().add(hiddenMenuBar, BorderLayout.CENTER);
    getContentPane().add(new JPanel(), BorderLayout.CENTER);*/
    nothingMenu = new JMenu("Nothing");
    nothingMenu.setMnemonic('N');
    nothingMenu.setFont(boldFont);
    nothingItem = new JMenuItem("NoAction");
    nothingItem.setFont(plainFont);
    nothingMenu.add(nothingItem);
    menuBar.add(nothingMenu);
    addMouseListener(new MouseAdaption());
    addKeyListener(new KeyAdaption());
  public static void main(String[] args)
    Dimension windowSize = new Dimension(300, 200);
    AnanyaCurves ananyaCurves = new AnanyaCurves(windowSize);
    ananyaCurves.pack();
    ananyaCurves.setBounds(0, 0, windowSize.width, windowSize.height);
    ananyaCurves.setVisible(true);
    ananyaCurves.requestFocus();
  public void exit()
    this.dispose();
    System.exit(0);
  class MouseAdaption extends MouseAdapter
    public void mousePressed(MouseEvent e)
      if (AnanyaCurves.this.alt == true)
        AnanyaCurves.this.exit();
  class KeyAdaption extends KeyAdapter
    public void keyPressed(KeyEvent event)
      /*int keyCode = event.getKeyCode();
      if (keyCode == KeyEvent.VK_ALT)
        AnanyaCurves.this.alt = true;
      else if (keyCode == KeyEvent.VK_E)
        AnanyaCurves.this.exit();
    public void keyReleased(KeyEvent event)
      AnanyaCurves.this.alt = false;
class Basics extends java.lang.Object
  public static AnanyaCurves ananyaCurves;
  public Basics()
class Command extends AbstractAction
  String name; // the command name (not the menu item string)
  String accelerator;
  public Command(String name, String accelerator)
    super();
    this.name = name;
    if (accelerator != null && !accelerator.equals(""))
      this.accelerator = accelerator;
      KeyStroke k = KeyStroke.getKeyStroke(accelerator);
      putValue(Action.ACCELERATOR_KEY, k);
  public void quit()
    Basics.ananyaCurves.dispose();
    System.exit(0);
  public void actionPerformed(ActionEvent actionEvent)
    try
      Method f = getClass().getMethod(this.name, (Class[])null);
      f.invoke(this, (Object[])null);
    catch (NoSuchMethodException e)
    catch (InvocationTargetException e)
    catch (IllegalAccessException e)
class CurveCanvas extends JPanel
  public CurveCanvas(Dimension docSize)
    super();
    Action altF = new AbstractAction()
      public void actionPerformed(ActionEvent e)
        Basics.ananyaCurves.alt = true;
    Action exitF = new AbstractAction()
      public void actionPerformed(ActionEvent e)
        Basics.ananyaCurves.exit();
    this.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("ALT"), "alt");
    this.getActionMap().put("alt", altF);
    this.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke("E"), "exit");
    this.getActionMap().put("exit", exitF);
In the getInputMap method I was trying to use the condition WHEN_IN_FOCUSED_WINDOW, hoping that the bound key would be recognized, but it didn't work. And, by the way, I still used the KeyAdapter so that the alt attribute of AnanyaCurves can be set to false when the ALT key is released.
I will appreciate your help very much! Thanks for your time!