@Override
        public void run(AnActionButton button) {
          final ExternalResourceManager erm = ExternalResourceManager.getInstance();
          final List<String> allURIs = new ArrayList<>(Arrays.asList(erm.getResourceUrls(null, true)));
          final Collection<Namespace> namespaces = myNamespaceTableModel.getNamespaces();
          for (Namespace namespace : namespaces) {
            allURIs.remove(namespace.getUri());
          }
          Collections.sort(allURIs);

          final DataContext dataContext = DataManager.getInstance().getDataContext(myNamespaceTable);
          final Project project = CommonDataKeys.PROJECT.getData(dataContext);
          final AddNamespaceDialog dlg = new AddNamespaceDialog(project, myUnresolvedPrefixes, allURIs, AddNamespaceDialog.Mode.EDITABLE);
          if (dlg.showAndGet()) {
            myNamespaceTableModel.addNamespace(new Namespace(dlg.getPrefix(), dlg.getURI()));
          }
        }
@Override
        public void run(AnActionButton button)