tree.getSelectionModel().setSelectionMode(
            TreeSelectionModel.SINGLE_TREE_SELECTION);
        }
      }

      if (JFileChooser.DIRECTORY_CHANGED_PROPERTY.equals(evt.getPropertyName())) {
        findFile(chooser.getCurrentDirectory(), false, false);
      }

      if (JFileChooser.ACCESSORY_CHANGED_PROPERTY.equals(evt.getPropertyName())) {
        Component oldValue = (Component)evt.getOldValue();
        Component newValue = (Component)evt.getNewValue();
        if (oldValue != null) {
          chooser.remove(oldValue);
        }
        if (newValue != null) {
          chooser.add("North", newValue);
        }
        chooser.revalidate();
        chooser.repaint();
      }

      if (JFileChooser.CONTROL_BUTTONS_ARE_SHOWN_CHANGED_PROPERTY.equals(evt
        .getPropertyName())) {
        updateView(chooser);
      }
      
      if (JDirectoryChooser.SHOWING_CREATE_DIRECTORY_CHANGED_KEY.equals(evt
        .getPropertyName())) {
        updateView(chooser);
      }
    }
  }

  private class SelectionListener implements TreeSelectionListener {

    public void valueChanged(TreeSelectionEvent e) {
      getApproveSelectionAction().setEnabled(tree.getSelectionCount() > 0);
      setSelectedFiles();

      // the current directory is the one currently selected
      TreePath currentDirectoryPath = tree.getSelectionPath();
      if (currentDirectoryPath != null) {
        File currentDirectory = ((FileTreeNode)currentDirectoryPath
          .getLastPathComponent()).getFile();
        chooser.setCurrentDirectory(currentDirectory);
      }
    }
  }

  public Action getApproveSelectionAction() {
    return approveSelectionAction;
  }

  private void setSelectedFiles() {
    TreePath[] selectedPaths = tree.getSelectionPaths();
    if (selectedPaths == null || selectedPaths.length == 0) {
      chooser.setSelectedFile(null);
      return;
    }

    List files = new ArrayList();
    for (int i = 0, c = selectedPaths.length; i < c; i++) {
      LazyMutableTreeNode node = (LazyMutableTreeNode)selectedPaths[i]
        .getLastPathComponent();
      if (node instanceof FileTreeNode) {
        File f = ((FileTreeNode)node).getFile();
        files.add(f);
      }
    }

    chooser.setSelectedFiles((File[])files.toArray(new File[0]));
  }

  private class ApproveSelectionAction extends AbstractAction {

    public ApproveSelectionAction() {
      setEnabled(false);
    }

    public void actionPerformed(ActionEvent e) {
      setSelectedFiles();
      chooser.approveSelection();
    }
  }

  /**
   * Listens on nodes being opened and preload their children to get
   * better UI experience (GUI should be more responsive and empty
   * nodes discovered automatically).
   */
  private class TreeExpansion implements TreeExpansionListener {

    public void treeCollapsed(TreeExpansionEvent event) {}

    public void treeExpanded(TreeExpansionEvent event) {
      // ensure children gets expanded later
      if (event.getPath() != null) {
        Object lastElement = event.getPath().getLastPathComponent();
        if (lastElement instanceof FileTreeNode && useNodeQueue) {
          if (((FileTreeNode)lastElement).isLoaded()) {
            enqueueChildren((FileTreeNode)lastElement);
          }
        }
      }
    }
  }

  private void enqueueChildren(FileTreeNode node) {
    for (Enumeration e = node.children(); e.hasMoreElements();) {
      addToQueue((FileTreeNode)e.nextElement(), tree);
    }
  }

  private class FileSystemTreeRenderer extends DefaultTreeCellRenderer {

    public Component getTreeCellRendererComponent(JTree tree, Object value,
      boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus) {
      super.getTreeCellRendererComponent(tree, value, sel, expanded, false,
      // even "leaf" folders should look like other folders
        row, hasFocus);

      if (value instanceof FileTreeNode) {
        FileTreeNode node = (FileTreeNode)value;
        setText(getFileView(chooser).getName(node.getFile()));
        // @PMD:REVIEWED:EmptyIfStmt: by fred on 14/08/04 17:25
        if (OS.isMacOSX() && UIManager.getLookAndFeel().isNativeLookAndFeel()) {
          // do not set icon for MacOSX when native look is used, it
          // seems the
          // Tree.icons set by the
          // look and feel are not that good or Apple is doing
          // something I
          // can't figure.
          // setIcon only if not running in MacOSX
        } else {
          setIcon(getFileView(chooser).getIcon(node.getFile()));
        }
      }

      return this;
    }
  }

  private class NewFolderAction extends AbstractAction {
    public void actionPerformed(ActionEvent e) {
      // get the currently selected folder
      JFileChooser fc = getFileChooser();
      File currentDirectory = fc.getCurrentDirectory();

      if (!currentDirectory.canWrite()) {
        JOptionPane.showMessageDialog(fc,
          UIManager
          .getString("DirectoryChooser.cantCreateFolderHere"),
          UIManager
          .getString("DirectoryChooser.cantCreateFolderHere.title"),
          JOptionPane.ERROR_MESSAGE);
        return;
      }
      
      String newFolderName = JOptionPane.showInputDialog(fc, UIManager
        .getString("DirectoryChooser.enterFolderName"), newFolderText,
        JOptionPane.QUESTION_MESSAGE);
      if (newFolderName != null) {
        File newFolder = new File(currentDirectory, newFolderName);
        if (newFolder.mkdir()) {
          if (fc.isMultiSelectionEnabled()) {
            fc.setSelectedFiles(new File[] {newFolder});
          } else {
            fc.setSelectedFile(newFolder);
          }
          fc.rescanCurrentDirectory();
        } else {
          JOptionPane.showMessageDialog(fc,
            UIManager
            .getString("DirectoryChooser.createFolderFailed"), UIManager
            .getString("DirectoryChooser.createFolderFailed.title"),
            JOptionPane.ERROR_MESSAGE);
        }
      }
    }
  }

  private class FileSystemTreeModel extends DefaultTreeModel {

    public FileSystemTreeModel(FileSystemView fsv) {
      super(new MyComputerTreeNode(fsv), false);
    }
  }

  private class MyComputerTreeNode extends LazyMutableTreeNode {

    public MyComputerTreeNode(FileSystemView fsv) {
      super(fsv);
    }

    protected void loadChildren() {
      FileSystemView fsv = (FileSystemView)getUserObject();
      File[] roots = fsv.getRoots();
      if (roots != null) {
        Arrays.sort(roots);
        for (int i = 0, c = roots.length; i < c; i++) {
          add(new FileTreeNode(roots[i]));
        }
      }
    }

    public String toString() {
      return "/";
    }
  }

  private class FileTreeNode extends LazyMutableTreeNode implements Comparable {

    public FileTreeNode(File file) {
      super(file);
    }

    public boolean canEnqueue() {
      return !isLoaded()
        && !chooser.getFileSystemView().isFloppyDrive(getFile())
        && !chooser.getFileSystemView().isFileSystemRoot(getFile());
    }

    public boolean isLeaf() {
      if (!isLoaded()) {
        return false;
      } else {
        return super.isLeaf();
      }
    }

    protected void loadChildren() {
      FileTreeNode[] nodes = getChildren();
      for (int i = 0, c = nodes.length; i < c; i++) {
        add(nodes[i]);
      }
    }

    private FileTreeNode[] getChildren() {
      File[] files =
        chooser.getFileSystemView().getFiles(
          getFile(),
          chooser.isFileHidingEnabled());
      ArrayList nodes = new ArrayList();
      // keep only directories, no "file" in the tree.
      if (files != null) {
        for (int i = 0, c = files.length; i < c; i++) {
          if (files[i].isDirectory()) {
            nodes.add(new FileTreeNode(files[i]));
          }
        }
      }
      // sort directories, FileTreeNode implements Comparable
      FileTreeNode[] result = (FileTreeNode[])nodes
        .toArray(new FileTreeNode[0]);
      Arrays.sort(result);
      return result;
    }

    public File getFile() {
      return (File)getUserObject();
    }

    public String toString() {
      return chooser.getFileSystemView().getSystemDisplayName(
        (File)getUserObject());
    }

    public int compareTo(Object o) {
      if (!(o instanceof FileTreeNode)) { return 1; }
      return getFile().compareTo(((FileTreeNode)o).getFile());
    }

    public void clear() {
      super.clear();
      ((DefaultTreeModel)tree.getModel()).nodeStructureChanged(this);
    }
  }

  /**
   * From WindowsFileChooserUI
   */
  protected class WindowsFileView extends BasicFileView {

    public Icon getIcon(File f) {
      Icon icon = getCachedIcon(f);
      if (icon != null) { return icon; }
      if (f != null) {
        icon = getFileChooser().getFileSystemView().getSystemIcon(f);
      }
      if (icon == null) {
        icon = super.getIcon(f);
      }
      cacheIcon(f, icon);
      return icon;
    }
  }

  private static synchronized void addToQueue(FileTreeNode node, JTree tree) {
    if (nodeQueue == null || !nodeQueue.isAlive()) {
      nodeQueue = new Queue();
      nodeQueue.start();
    }
    if (node.canEnqueue()) {
      nodeQueue.add(node, tree);
    }
  }

  /**
   * This queue takes care of loading nodes in the background.
   */
  private static final class Queue extends Thread {

    private volatile Stack nodes = new Stack();

    private Object lock = new Object();

    private volatile boolean running = true;

    public Queue() {
      super("DirectoryChooser-BackgroundLoader");
      setDaemon(true);
    }

    public void add(WindowsDirectoryChooserUI.FileTreeNode node, JTree tree) {
      if (!isAlive()) {
        throw new IllegalArgumentException("Queue is no longer alive");
      }

      synchronized (lock) {
        if (running) {
          nodes.addElement(new QueueItem(node, tree));
          lock.notifyAll();
        }
      }
    }

    public void run() {
      while (running) {
        while (nodes.size() > 0) {
          final QueueItem item = (QueueItem)nodes.pop();
          final WindowsDirectoryChooserUI.FileTreeNode node = item.node;
          final JTree tree = item.tree;

          // ask how many items we got
          node.getChildCount();

          Runnable runnable = new Runnable() {

            public void run() {
              ((DefaultTreeModel)tree.getModel()).nodeChanged(node);
              tree.repaint();
            }
          };
          try {
            SwingUtilities.invokeAndWait(runnable);
          } catch (InterruptedException e) {
            e.printStackTrace();
          } catch (InvocationTargetException e) {
            e.printStackTrace();
          }
        }

        // wait for 5 seconds for someone to use the queue, else just
        // ends this
        // queue
        try {
          synchronized (lock) {
            lock.wait(5000);
          }

          if (nodes.size() == 0) {
            running = false;
          }

        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }
  }

  /**
   * An entry in the queue.
   */
  private static final class QueueItem {
    WindowsDirectoryChooserUI.FileTreeNode node;
    JTree tree;
    public QueueItem(WindowsDirectoryChooserUI.FileTreeNode node, JTree tree) {
      this.node = node;
      this.tree = tree;
    }
  }

}