title: How to update Kivy ActionGroup display when a widget is added to it?
body: <p>I am currently trying to add, remove, and display the contents/widgets dynamically in an ActionGroup widget. When I try to add an ActionButton to an ActionGroup, the widget gets added to the ActionGroup. However when I click the ActionGroup (spinner mode) on program test run, the widget that I added was not shown. It only shows when I resize the App window, forcing it to refresh then allow the ActionButton that I added to be shown. How can I make that when I add an ActionButton it is shown immediately and not make me do some resizing on the App window just to make it appear.</p>
  
  <p>I tried looking on how to refresh the ActionBar or the ActionView similar on how it refreshes when I try to resize the window. However the documentation does not show any methods on how to make it.</p>
  
  <p><strong>python code</strong></p>
  
  <pre><code>class ThirstyWellRoot(BoxLayout):
       def create_graph(self, port):
          graph_controller = GraphController(port, name=port.port_name)
          action_button = ActionButton(text=port.port_name)
          self.screen_manager.add_widget(graph_controller)
          self.action_group.add_widget(action_button)
  </code></pre>
  
  <p><strong>kv code</strong></p>
  
  <pre><code>&lt;ThirstyWellRoot&gt;:
      action_group: action_group
      screen_manager: screen_manager
      orientation: 'vertical'
      canvas:
          Color:
              rgba: tertiary_color
          Rectangle:
              size: self.size
              pos: self.pos
      ScreenManager:
          id: screen_manager
      ActionBar:
          height: 50
          ActionView:
              id: action_view
              use_separator: True
              ActionPrevious:
                  with_previous: False
                  app_icon: 'assets/theme/logo.png'
                  on_release: root.about()
              ActionGroup:
                  id: action_group
                  mode: 'spinner'
                  text: 'PORTS'
              ActionGroup:
                  text: 'DISPLAY'
                  ActionButton:
                      text: 'ADD'
                      on_release: root.add_connection()
                  ActionButton:
                      text: 'OPEN'
                      on_release: root.open_graph()
                  ActionButton:
                      text: 'REMOVE'
                      on_release: root.remove_graph()
              ActionGroup:
                  text: 'COMMANDS'
                  ActionButton:
                      text: 'MONITOR'
                  ActionButton:
                      text: 'STOP'
                  ActionButton:
                      text: 'RESET'
  </code></pre>
  
  <p>The expected would be that as I add the ActionButton to the ActionGroup, the widget that I added should be visible immediately as I press the ActionGroup (spinner mode). However, it does not show immediately and it only shows when I resize the window, forcing it to overflow (ActionOverflow from ActionView) and show the ActionButton that I added.</p>
  
  <p>As I add the button</p>
  
  <p><a href="https://i.stack.imgur.com/wZ7T0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wZ7T0.png" alt="As I add the button"></a></p>
  
  <p>After I added the button it does not show up as I press the ActionGroup</p>
  
  <p><a href="https://i.stack.imgur.com/J3X5U.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J3X5U.png" alt="After I add the button it does not show up as I press the ActionGroup"></a></p>
  
  <p>It only shows up when I tried few minimize and maximize window commands</p>
  
  <p><a href="https://i.stack.imgur.com/ASbN1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ASbN1.png" alt="It only shows up when I tried few minimize and maximize window commands"></a></p>