title: Switch BoxLayout to vertical in Kivy and get widgets by id in Python code
body: <p>I am creating an Accordion widget on hitting enter on a text-input.</p>
  
  <p>Following is the python code:</p>
  
  <pre><code>class LabelNavigatorWidget(BoxLayout):
      def create_accordion_widget(self):
          self.cleanup_root()
          root = Accordion(id='accordion_widget', orientation='vertical')
          for x in range(2):
              item = AccordionItem(title='Title %d' % x)
              item.add_widget(Label(text='Very big content\n' * 10))
              root.add_widget(item)
          self.add_widget(root)
          return root
  
      def cleanup_root(self):
          # Remove previous widget
          for child in self.children:
              if child.id == 'accordion_widget':
                  self.remove_widget(child)
  
  class LabelNavigatorApp(App):
      def build(self):
          return LabelNavigatorWidget()
  
  if __name__ == "__main__":
      LabelNavigatorApp().run()
  </code></pre>
  
  <p>Below is the kv code:</p>
  
  <pre><code>&lt;LabelNavigatorWidget&gt;:
      BoxLayout:
          orientation: 'vertical'
          TextInput:
              id: label_input
              font_size: 30
              pos: 0, 0
              size_hint_y: None
              height: 50
              multiline: False
              text: ''
              on_text_validate: root.create_accordion_widget(); self.text = ''
  </code></pre>
  
  <p>This is how it looks:</p>
  
  <p><img src="https://i.stack.imgur.com/i9gk5.png" alt="Incorrect BoxLayout"></p>
  
  <ol>
  <li>So, the default BoxLayout is horizontal, how can I set it to vertical ?</li>
  <li>The initial location of the text-input is at the bottom of the BoxLayout, how can I make it sit at the top ?</li>
  <li>Whenever, I hit enter, it will create a new accordion widget - that is why I am removing the previous widget before I create a new one. However, is there a better way to get the child widget (say by id?) and then remove it instead of iterating through all children ?</li>
  </ol>