title: black screen simple kivy with colab
body: <p>I have made a simple app with kivy, just to test how to create a .apk and using colab to compile I get a black screen on my phone and in BlueStacks.
  This is the app:</p>
  <p>main.py:</p>
  <pre><code>from kivy.app import App
  from kivy.uix.boxlayout import BoxLayout
  from kivy.uix.widget import Widget
  
  
  class BoxLayoutMain(BoxLayout):
      pass
  
  class MainWidget(Widget):
      pass
  
  class dctApp(App):
      pass
  
  dctApp().run()
  </code></pre>
  <p>and dctApp.kv:</p>
  <pre><code>BoxLayoutMain:
  
  &lt;MainWidget&gt;:
  
  &lt;BoxLayoutMain&gt;:
      orientation: &quot;vertical&quot;
  
      Label:
          text: &quot;Lash&quot;
          font_name: &quot;fonts/DINNeuzeitGrotesk-Light Regular.ttf&quot;
          font_size: &quot;40dp&quot;
          size_hint: 1, 0.1
          background_color: (255/255, 142/255, 142/255, 1)
          canvas.before:
              Color:
                  rgba: self.background_color
              Rectangle:
                  size: self.size
                  pos: self.pos
  
  
      Carousel:
          direction: &quot;bottom&quot;
  
          Button:
              text: &quot;this is a test&quot;
  
      BoxLayout:
          orientation: &quot;horizontal&quot;
          size_hint: 1, 0.1
  
          Button:
              text: &quot;B&quot;
              background_normal: &quot;&quot;
              background_color: (255/255, 142/255, 142/255, 255/255)
  
          Button:
              text: &quot;B&quot;
              background_normal: &quot;&quot;
              background_color: (255/255, 142/255, 142/255, 255/255)
  
          Button:
              text: &quot;B&quot;
              background_normal: &quot;&quot;
              background_color: (255/255, 142/255, 142/255, 255/255)
  </code></pre>
  <p>It's basically a .py file and a .kv file to show some items. When I run it in Pycharm it works fine, but when I create the .apk in Colab, it's just black.
  Please help! I have no idea what to do!
  Thank you</p>