private void update() {
    RepositoryTreeNode baseNode = myBrowser.getSelectedNode();
    if (baseNode == null) {
      myErrorLabel.setText(message("diff.options.no.url.error"));
      getOKAction().setEnabled(false);
      return;
    }
    if (myURL.equals(getTargetURL())) {
      myErrorLabel.setText(message("diff.options.same.url.error"));
      getOKAction().setEnabled(false);
      return;
    }
    if (myUnifiedDiffButton.isSelected() && (myFileBrowser.getText().length() == 0 || getTargetFile().getParentFile() == null)) {
      myErrorLabel.setText(message("diff.options.no.patch.file.error"));
      getOKAction().setEnabled(false);
      return;
    }
    myErrorLabel.setText(" ");
    getOKAction().setEnabled(true);
  }
private void update()