title: Kivy ScrollView+Accordion Error
body: <p>I have this code. If I increase the number of Accordion items past a certain amount the app goes haywire. The gridLayout version (commented out) works as expected. The offending region is between HERE and THERE.</p>
  
  <pre><code>from kivy.app import App
  from kivy.uix.spinner import Spinner, SpinnerOption
  from kivy.uix.boxlayout import BoxLayout
  from kivy.uix.accordion import Accordion, AccordionItem
  from kivy.uix.label import Label
  from kivy.uix.button import Button
  from kivy.uix.scrollview import ScrollView
  from kivy.uix.gridlayout import GridLayout
  from kivy.core.window import Window
  
  class MusicController(App):
  
      def build(self):
          b = BoxLayout(orientation='vertical')
          top = Spinner(text = '12', values = ["Songs","Artist","Playlist","Search"], background_color = (.3,.2,.5,1), size_hint_y = 0.1)
  
      #&lt; HERE &gt;#
  
          items = Accordion(orientation='vertical')
          for x in xrange(30):
              item = AccordionItem(title='Title %d' % x)
              buttons = BoxLayout()
              buttons.add_widget(Button(text='Play'))
              buttons.add_widget(Button(text='Pause'))
              buttons.add_widget(Button(text='Pause'))
              item.add_widget(buttons)
              items.add_widget(item)
  
          #~ items = GridLayout(cols=1, spacing=10, size_hint_y=None)
          #~ items.bind(minimum_height=items.setter('height'))
          #~ for i in range(30):
              #~ btn = Button(text=str(i), 
  
      #&lt; THERE &gt;#
  
          sv = ScrollView(do_scroll_x = False)
          sv.add_widget(items)
          now_playing = BoxLayout(size_hint_y = 0.1)
          for widget in ["Prev","Play","Pause","Next","NP"]:
              now_playing.add_widget(Button(text=widget))
  
          b.add_widget(top)
          b.add_widget(sv)
          b.add_widget(now_playing)
          return b
  
  if __name__ == '__main__':
      MusicController().run()
  </code></pre>