public void valueChanged(TreeSelectionEvent e) {
      TreePath[] paths = e.getPaths();

      boolean enabled = true;
      for (TreePath treePath : paths) {
        if (!e.isAddedPath(treePath)) {
          continue;
        }
        DefaultMutableTreeNode node = (DefaultMutableTreeNode) treePath.getLastPathComponent();
        Object userObject = node.getUserObject();
        if (!(userObject instanceof FileNodeDescriptor)) {
          enabled = false;
          break;
        }
        FileElement descriptor = ((FileNodeDescriptor) userObject).getElement();
        VirtualFile file = descriptor.getFile();
        enabled = file != null && myChooserDescriptor.isFileSelectable(file);
      }
      setOKActionEnabled(enabled);
    }
  /**
   * Returns list cell renderer component.
   *
   * @param list tree
   * @param value cell value
   * @param index cell index
   * @param isSelected whether cell is selected or not
   * @param cellHasFocus whether cell has focus or not
   * @return cell renderer component
   */
  @Override
  public Component getListCellRendererComponent(
      final JList list,
      final Object value,
      final int index,
      final boolean isSelected,
      final boolean cellHasFocus) {
    super.getListCellRendererComponent(list, "", index, isSelected, cellHasFocus);

    final FileElement element = (FileElement) value;
    final File file = element.getFile();

    // Proper margin
    setMargin(isTilesView() ? tileCellMargin : iconCellMargin);

    // Renderer icon
    String imageSize = null;
    if (iconLabel.isEnabled()) {
      // Thumbnail loading
      synchronized (thumbnailsLock) {
        if (!element.isThumbnailQueued() && !element.isDisabledThumbnailQueued()) {
          queueThumbnailLoad(element, false);
        }
      }

      // Image thumbnail
      final ImageIcon thumbnail = element.getEnabledThumbnail();
      iconLabel.setIcon(thumbnail);

      // Image description
      if (thumbnail != null) {
        imageSize = thumbnail.getDescription();
      }
    } else {
      // Disabled thumbnail loading
      synchronized (thumbnailsLock) {
        if (!element.isDisabledThumbnailQueued()) {
          queueThumbnailLoad(element, true);
        }
      }

      // Image disabled thumbnail
      iconLabel.setDisabledIcon(element.getDisabledThumbnail());
    }

    // Updating file description elements
    if (fileList.getEditedCell() != index) {
      // Settings description
      final FileDescription fileDescription = FileUtils.getFileDescription(file, imageSize);
      nameLabel.setText(fileDescription.getName());

      // Updating tile view additional description
      if (isTilesView()) {
        descriptionLabel.setText(fileDescription.getDescription());

        // Updating size label
        if (fileDescription.getSize() != null) {
          sizeLabel.setText(fileDescription.getSize());
        } else {
          sizeLabel.setText(null);
        }
      } else {
        descriptionLabel.setText(null);
        sizeLabel.setText(null);
      }
    } else {
      nameLabel.setText(null);
      descriptionLabel.setText(null);
      sizeLabel.setText(null);
    }

    return this;
  }