private void queueUpdateByProblem() {
   if (Registry.is("projectView.showHierarchyErrors")) {
     if (myTreeBuilder != null) {
       myTreeBuilder.queueUpdate();
     }
   }
 }
 @Override
 public ActionCallback getReady(@NotNull Object requestor) {
   if (myTreeBuilder == null || myTreeBuilder.isDisposed()) return new ActionCallback.Rejected();
   return myTreeBuilder.getUi().getReady(requestor);
 }