@Nullable
  public Url getRootUrl() {
    RepositoryTreeNode node = myRepositoryBrowser.getSelectedNode();

    // find the most top parent of type RepositoryTreeNode
    while (node != null && node.getParent() instanceof RepositoryTreeNode) {
      node = (RepositoryTreeNode)node.getParent();
    }

    return node != null ? node.getURL() : null;
  }
@Nullable
  public Url getRootUrl()