code: public void onCategoriesTabSelection() {
  
          if (!m_galleryDialog.getCategoriesTab().isInitOpen()) {
              m_galleryDialog.getCategoriesTab().onContentChange();
              return;
          }
          m_galleryDialog.getCategoriesTab().openFirstLevel();
          m_galleryDialog.getCategoriesTab().setInitOpen(false);
      }
docs: Will be triggered when the categories tab is selected.<p>