title: Kivy Button in Popup not calling function
body: <p>Here's the code that has the problem:</p>
  
  <pre><code>Class Screen1(Screen):
      def win(self):
          if win == True:
               Self.open_popup()
  
      def open_popup(self):
          content = BoxLayout()
          button = Button(text="restart", on_press=self.retry(), 
          on_release=self.dismiss() )
          content.add_widget(button)
          self.popup = Popup(title="Popup", content=content)
  
      def retry(self):
          #resets game
  </code></pre>
  
  <p>It gives me the error "none is not callable" and "Screen1 has no attribute dismiss" what am I doing wrong?</p>
  
  <p>Also, I have had to call the popup like this and not in a .kv file because that for some reason didn't work with screen manager </p>