class AppDialog(ModalView):
    def add_widget(self, *args, **kwargs):
        if self.children:
            return self.children[0].add_widget(*args, **kwargs)
        return super(AppDialog, self).add_widget(*args, **kwargs)
    
    def remove_widget(self, *args, **kwargs):
        if self.children:
            return self.children[0].remove_widget(*args, **kwargs)
        return super(AppDialog, self).remove_widget(*args, **kwargs)
    
    def clear_widgets(self, *args, **kwargs):
        if self.children:
            return self.children[0].clear_widgets(*args, **kwargs)
        return super(AppDialog, self).clear_widgets(*args, **kwargs)