public void free() {
   AlbumConstants.LOG.info("main free: " + this);
   if (mPreviewer != null) {
     mPreviewer.kill();
   }
   mTreeView.free();
   mContentView.free();
 }
  public FolderBrowserWindow(AlbumUI pUI, VaadinRequest pRequest) {
    mContentView = new FolderContentView(mPusher, this);
    mTreeView = new FolderTreeView(mPusher, mContentView);

    {
      mPreviewLabel = new Label("", Label.CONTENT_RAW);

      VerticalLayout layout = new VerticalLayout();
      layout.setHeight("100%");

      layout.addComponent(mPreviewLabel);
      mPreviewView = layout;
    }
    createLayout(pRequest);

    mTreeView.setRootDir(AlbumConstants.DISPLAY_PATH.getPath());
    mTreeView.showDir(mTreeView.getRootDir());

    mPusher.extend(pUI);
  }