code: public void addTopWidget(Widget w) {
  
          m_content.removeStyleName(I_CmsLayoutBundle.INSTANCE.dialogCss().alertMainContent());
          m_topWidgets.getElement().getStyle().clearDisplay();
          m_topWidgets.add(w);
      }
docs: Adds a widget to this dialogs top content.<p>
  
  @param w the widget to add