code: private void initButtonPanel() {
  
          if ((m_buttonPanel == null) && m_isFrame) {
              m_buttonPanel = new FlowPanel();
              m_buttonPanel.addStyleName(I_CmsLayoutBundle.INSTANCE.dialogCss().popupButtonPanel());
              m_main.add(m_buttonPanel);
          }
      }
docs: Initializes the button panel within frame mode.<p>