bug report for kivy - ScrollView.bind(scroll_y=x)

main.py

from kivy.lang import Builder
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView
from kivy.uix.label import Label
from kivy.clock import Clock

class TestApp(App):
 
    def build(self):
        self.box = BoxLayout()
        # kanalid = BoxLayout()
        self.vasak_kast = ScrollView(size_hint = (None,1), size_x=150)
        self.parem_kast = ScrollView()
        self.vasak_kast.bind(scroll_y=self.parem_kast.scroll_y)
 
        self.grid_vasak = GridLayout(size_hint = (1,3), cols=1)
        self.grid_parem = GridLayout(size_hint = (1,3), cols=1)
 
        self.box.add_widget(self.vasak_kast)
        self.box.add_widget(self.parem_kast)
        self.vasak_kast.add_widget(self.grid_vasak)
        self.parem_kast.add_widget(self.grid_parem)
        self.grid_vasak.add_widget(Label(text='Logod'))
        self.grid_parem.add_widget(Label(text='Kanalid'))
        self.vasak_kast.bind(scroll_y=self.parem_kast.scroll_y)
        Clock.schedule_interval(self.print_scrolls, 1)
 
        for i in range(20):
            self.grid_parem.add_widget(Button(text='kanal %s'%i))
        for i in range(20):
            self.grid_vasak.add_widget(Button(text='Pilt %s'%i))

        return self.box

    def print_scrolls(self, arg1):
        print '-------------------------'
        print self.parem_kast.scroll_y
        print self.vasak_kast.scroll_y

if __name__ == '__main__':
    TestApp().run()