book.kv

#:kivy 1.5.1

FloatLayout:
	size_hint: (1,1)
	bookcover: bookcover
	Carousel:
		pos_hint: {'center_x': 0.5, 'top': app.booky}
		size_hint: (1,1)
		id: bookcover

library.kv

#:kivy 1.5.1

GridLayout:
    cols: 3
    librarybook: librarybook
    id: librarybook
    Button
    Button
    Button:
        text: 'Book1'
        on_press: app.build_book()
    Button
    Button
    Button

main.py

'''
Carousel example with button inside.
This is a tiny test for testing the scroll distance/timeout
And ensure the down/up are dispatched if no gesture is done.
'''
from kivy.uix.carousel import Carousel
from kivy.uix.gridlayout import GridLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.uix.button import Button
from kivy.properties import ObjectProperty, StringProperty, NumericProperty, BooleanProperty
from kivy.core.window import Window


class dragB(Button):

    def __init__(self, **kwargs):
        super(dragB, self).__init__(**kwargs)
        self.size_hint= (0.8,0.1)
        self.pos_hint= {'center_x': 0.5, 'top': 1}
        self.background_color=(1,0,0,1)

    def on_touch_move(self, touch):
        b = App.get_running_app().booky
        newpos = b-(b-touch.y/Window.size[1])/3
        if self.state == 'down':
            App.get_running_app().booky =  newpos
            self.pos_hint= {'center_x': 0.5, 'top': newpos}
        print App.get_running_app().Book.bookcover


class InsertBookApp(App):
    # Define containers
    container                   = ObjectProperty(None)
    bookcover                   = ObjectProperty(None)
    librarybook                 = ObjectProperty(None)

    # variables
    booky = NumericProperty(1)

    def build(self):
        # load kv files
        self.root               = Builder.load_file('root.kv')
        self.Book               = Builder.load_file('book.kv')
        self.Library            = Builder.load_file('library.kv')
        


        # connect containers
        self.container          = self.root.container
        self.bookcover          = self.Book.bookcover
        self.librarybook        = self.Library.librarybook

        self.root.add_widget(self.Library)
        return self.root

    def build_book(self):
        self.bookcover.add_widget(Button(text='page1', background_color=(0,1,0,1)))
        self.bookcover.add_widget(Button(text='page2', background_color=(0,1,0,1)))
        self.bookcover.add_widget(Button(text='page3', background_color=(0,1,0,1)))
        self.bookcover.add_widget(Button(text='page4', background_color=(0,1,0,1)))
        self.root.add_widget(self.Book)
        self.root.add_widget(dragB())
        print self

    def drag_book(self, btn):
        print btn

    def drag_book_stop(self, btn):
        print 'release'


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

root.kv

#:kivy 1.5.1

FloatLayout:
	container: container
	id: container
	canvas.before:
		Color:
			rgb: .25,.3,.4,1