Help with understanding key event propagation

Question

Hello,
I am hoping someone can help me understand a few things which are not clear to me with respect to handling of key events by Swing components. My understanding is summarized as:
(1) Components have 3 input maps which map keys to actions
one for when they are the focused component
one for when they are an ancestor of the focused component
one for when they are in the same window as the focused component
(2) Components have a single action map which contains actions to be fired by key events
(3) Key events go to the currently focused component
(4) Key events are consumed by the first matching action that is found
(5) Key events are sent up the containment hierarchy up to the window (in which case components with a matching mapping in the WHEN_IN_FOCUSED_WINDOW map are searched for)
(6) The first matching action handles the event which does not propagate further
I have a test class (source below) and I obtained the following console output:
Printing keyboard map for Cancel button
Level 0
Key: pressed C
Key: released SPACE
Key: pressed SPACE
Level 1
Key: pressed SPACE
Key: released SPACE
Printing keyboard map for Save button
Level 0
Key: pressed SPACE
Key: released SPACE
Level 1
Key: pressed SPACE
Key: released SPACE
Printing keyboard map for Main panel
Event: cancel // typed SPACE with Cancel button having focus
Event: save // typed SPACE with Save button having focus
Event: panel // typed 'C' with panel having focus
Event: panel // typed 'C' with Cancel button having focus
Event: panel // typed 'C' with Save button having focus
I do not understand the following aspects of its behaviour (tested on MacOSX although I believe the behaviour is not platform dependent):
(1) I assume that the actions are mapped to SPACE since the spacebar clicks the focused component but I don't explicitly set it?
(2) assuming (1) is as I described why are there two mappings, one for key pressed and one for key released yet the 'C' key action only has a key pressed set?
(3) assuming (1) and (2) are true then why don't I get the action fired twice when I typed the spacebar, once when I pressed SPACE and again when I released SPACE?
(4) I read that adding a dummy action with the value "none" (i.e. the action is the string 'none') should hide the underlying mappings for the given key, 'C' the my example so why when I focus the Cancel button and press the 'C' key do I get a console message from the underlying panel action (the last but one line in the output)?
Any help appreciated. The source is:
import javax.swing.*;
public class FocusTest extends JFrame {
     public FocusTest ()     {
          initComponents();
          setTitle ("FocusTest");
          setLocationRelativeTo (null);
          setSize(325, 160);
          setVisible (true);
     public static void main (String[] args) {
          new FocusTest();
private void initComponents()
     JPanel panTop = new JPanel();
          panTop.setBackground (java.awt.Color.RED);
JLabel lblBanner = new javax.swing.JLabel ("PROPERTY TABLE");
lblBanner.setFont(new java.awt.Font ("Lucida Grande", 1, 14));
lblBanner.setHorizontalAlignment (javax.swing.SwingConstants.CENTER);
          panTop.add (lblBanner);
          JPanel panMain = new JPanel ();
          JLabel lblKey = new JLabel ("Key:");
          lblKey.setFocusable (true);
          JLabel lblValue = new JLabel ("Value:");
JTextField tfKey = new JTextField(20);
JTextField tfValue = new JTextField(20);
JButton btnCancel = new JButton (createAction("cancel"));     // Add a cancel action.
JButton btnSave = new JButton (createAction("save"));          // Add a sve action.
          panMain.add (lblKey);
          panMain.add (tfKey);
          panMain.add (lblValue);
          panMain.add (tfValue);
          panMain.add (btnCancel);
          panMain.add (btnSave);
          add (panTop, java.awt.BorderLayout.NORTH);
          add (panMain, java.awt.BorderLayout.CENTER);
setDefaultCloseOperation (javax.swing.WindowConstants.EXIT_ON_CLOSE);
// Add an action to the panel for the C key.
          panMain.getInputMap (JComponent.WHEN_IN_FOCUSED_WINDOW).put (KeyStroke.getKeyStroke (java.awt.event.KeyEvent.VK_C, 0), "panel");
          panMain.getActionMap ().put ("panel", createAction("panel"));
          // FAILS ???
          // Add an empty action to the Cancel button to block the underlying panel C key action.
btnCancel.getInputMap().put (KeyStroke.getKeyStroke (java.awt.event.KeyEvent.VK_C, 0), "none");
// Print out the input map contents for the Cancel and Save buttons.
System.out.println ("\nPrinting keyboard map for Cancel button");
printInputMaps (btnCancel);
System.out.println ("\nPrinting keyboard map for Save button");
printInputMaps (btnSave);
          // FAILS NullPointer because the map contents are null ???
System.out.println ("\nPrinting keyboard map for Main panel");
// printInputMaps (panMain);
private AbstractAction createAction (final String actionName) {
     return new AbstractAction (actionName) {
          public void actionPerformed (java.awt.event.ActionEvent evt) {
               System.out.println ("Event: " + actionName);
private void printInputMaps (JComponent comp) {
     InputMap map = comp.getInputMap();
     printInputMap (map, 0);
private void printInputMap (InputMap map, int level) {
     System.out.println ("Level " + level);
     InputMap parent = map.getParent();
     Object[] keys = map.allKeys();
     for (Object key : keys) {
          if (key.equals (parent)) {
               continue;
          System.out.println ("Key: " + key);
     if (parent != null) {
          level++;
          printInputMap (parent, level);
Thanks,
Tim Mowlem

Answer 1

Use the [url http://forum.java.sun.com/help.jspa?sec=formatting]Code Formatting Tags so the posted code retains its original formatting.
1) In the Metal LAF the space bar activates the button. In the Windows LAF the Enter key is used to activate the button. Therefore these bindings are added by the LAF.
2) The pressed binding paints the button in its pressed state. The released binding paint the button in its normal state. Thats why the LAF adds two bindings.
In your case you only added a single binding.
3) The ActionEvent is only fired when the key is released. Same as a mouse click. You can hold the mouse down as long as you want and the ActionEvent isn't generated until you release the mouse. In fact, if you move the mouse off of the button before releasing the button, the ActionEvent isn't even fired at all. The mouse pressed/released my be generated by the same component.
4) Read (or reread) the [url http://java.sun.com/docs/books/tutorial/uiswing/misc/keybinding.html#howto]How to Remove Key Bindings section. "none" is only used to override the default action of a component, it does not prevent the key stroke from being passed on to its parent.