code: def display_popup(self, title, content):
          
          assert isinstance(title, six.text_type)
          assert isinstance(content, six.text_type)
  
          self.popup_dialog.title = title
          self._popup_textarea.text = content
          self.client_state.display_popup = True
          get_app().layout.focus(self._popup_textarea)
docs: Display a pop-up dialog.