Kivy: asynchronous popups

asyncpopup.py

import kivy
kivy.require('1.8.0')

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.popup import Popup

from twisted.internet import defer

class DeferredPopup(Popup):
    def __init__(self, **kwargs):
        super(DeferredPopup, self).__init__(**kwargs)
        self.d = None
    
    def show(self, *args, **kwargs):
        self.d = defer.Deferred()
        self.open(*args, **kwargs)
        return self.d
    
    def on_ok(self):
        try:
            result = self.get_result()
        except Exception:
            return
        
        self.d.callback(result)
        self.dismiss()
    
    def on_cancel(self):
        self.d.callback(None)
        self.dismiss()
    
    def get_result(self):
        raise NotImplementedError

class MyPopup(DeferredPopup):
    def get_result(self):
        return True

root = Builder.load_string('''
<MyPopup>:
    BoxLayout:
        orientation: 'vertical'
        
        Label:
            text: 'Hello!'
        
        BoxLayout:
            size_hint_y: None
            height: sp(72)
            
            Button:
                text: 'OK'
                on_press: root.on_ok()
            Button:
                text: 'Cancel'
                on_press: root.on_cancel()

BoxLayout:
    Button:
        text: 'Open Popup'
        on_press: app.open_popup()
''')

class TestApp(App):
    def build(self):
        return root
    
    @defer.inlineCallbacks
    def open_popup(self):
        print 'open popup'
        p = MyPopup()
        result = yield p.show()
        print 'popup closed'
        print 'result:', result

if __name__ == '__main__':
    from kivy.support import install_twisted_reactor
    install_twisted_reactor()
    TestApp().run()