title: Kivy Label and Popup + long text
body: <p>So I am trying to show some long text in a Popup. It would be ideal if the height of the Popup could change for the length of text. But that's not my only problem I've tried to implement this without the size change with this code</p>
  
  <pre><code>    boxl = uix.boxlayout.BoxLayout(orientation="vertical")
      boxl2 = uix.boxlayout.BoxLayout(orientation="horizontal")
      pop = Popup(title="Title", content=boxl, size_hint=(0.75,0.8))
      text = "Really long text"
  
      document = uix.label.Label(text=text,markup=True, valign='top')
  
      button = uix.button.Button(text='back', size_hint_y=None, height=40)
      button2 = uix.button.Button(text="Button Title", size_hint_y=None, height=40)
      button.bind(on_press=(lambda x:pop.dismiss()))
      button2.bind(on_press=(lambda x,data=data:(self.set_vorteil(data),pop.dismiss())))
      boxl.add_widget(document)
  
      boxl2.add_widget(button)
      boxl2.add_widget(button2)
      boxl.add_widget(boxl2)
      document.bind(size=document.setter('text_size'))
      pop.open()
  </code></pre>
  
  <p>The interesting thing with this is that my text is cut off, even if there is a huge free space before the buttons. How do I fix this or even make it right? I'm confused with Kivy's way of using Labels.</p>