Move between screens (Python 3.6, Kivy 1.9.1)

Question

I need help with move between screens. I need 5 screens (MainWindow, Button1, Button2, Button3, Button4) from MainWindow move to Button screens and from button screens move back to MainWindow. I have problem when I press one of 4 buttons console returns error.

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.button import Button
from kivy.core.window import Window

Window.size = (400,650)


class MainWindow(FloatLayout):
    def __init__(self, **kwargs):
        super(MainWindow, self).__init__(**kwargs)

        # Main Label
        label_position = AnchorLayout(anchor_x='center',
                                      anchor_y='top')
        label_settings = Label(text='> > > MyOrganiser MainWindow < < <',
                               size=(200, 50),
                               size_hint=(None, None))
        label_position.add_widget(label_settings)
        self.add_widget(label_position)

        # Main Menu button 1
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='center')
        button_settings = Button(text='button1',
                                 size=(200, 200),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=Button1)

        # Main Menu button 2
        button_position = AnchorLayout(anchor_x='right',
                                       anchor_y='center')
        button_settings = Button(text='button2',
                                 size=(200, 200),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=Button2)

        # Main Menu button 3
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='bottom')
        button_settings = Button(text='button3',
                                 size=(200, 200),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=Button3)

        # Main Menu button 4
        button_position = AnchorLayout(anchor_x='right',
                                       anchor_y='bottom')
        button_settings = Button(text='button4',
                                 size=(200, 200),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=Button4)


class Button1(FloatLayout):
    def __init__(self, **kwargs):
        super(Button1, self).__init__(**kwargs)

        # Window Button1 Label
        label_position = AnchorLayout(anchor_x='center',
                                      anchor_y='top')
        label_settings = Label(text='> > > MyOrganiser Button1 < < <',
                               size=(200, 50),
                               size_hint=(None, None))
        label_position.add_widget(label_settings)
        self.add_widget(label_position)

        # back button for Button1 window
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='bottom')
        button_settings = Button(text='back',
                                 size=(100, 50),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=MainWindow)


class Button2(FloatLayout):
    def __init__(self, **kwargs):
        super(Button2, self).__init__(**kwargs)

        # Window Button2 Label
        label_position = AnchorLayout(anchor_x='center',
                                      anchor_y='top')
        label_settings = Label(text='> > > MyOrganiser Button2 < < <',
                               size=(200, 50),
                               size_hint=(None, None))
        label_position.add_widget(label_settings)
        self.add_widget(label_position)

        # back button for Button2 window
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='bottom')
        button_settings = Button(text='back',
                                 size=(100, 50),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=MainWindow)


class Button3(FloatLayout):
    def __init__(self, **kwargs):
        super(Button3, self).__init__(**kwargs)

        # Window Button3 Label
        label_position = AnchorLayout(anchor_x='center',
                                      anchor_y='top')
        label_settings = Label(text='> > > MyOrganiser Button3 < < <',
                               size=(200, 50),
                               size_hint=(None, None))
        label_position.add_widget(label_settings)
        self.add_widget(label_position)

        # back button for Button3 window
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='bottom')
        button_settings = Button(text='back',
                                 size=(100, 50),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=MainWindow)


class Button4(FloatLayout):
    def __init__(self, **kwargs):
        super(Button4, self).__init__(**kwargs)

        # Window Button4 Label
        label_position = AnchorLayout(anchor_x='center',
                                      anchor_y='top')
        label_settings = Label(text='> > > MyOrganiser Button4 < < <',
                               size=(200, 50),
                               size_hint=(None, None))
        label_position.add_widget(label_settings)
        self.add_widget(label_position)

        # back button for Button4 window
        button_position = AnchorLayout(anchor_x='left',
                                       anchor_y='bottom')
        button_settings = Button(text='back',
                                 size=(100, 50),
                                 size_hint=(None, None))
        button_position.add_widget(button_settings)
        self.add_widget(button_position)

        button_settings.bind(on_press=MainWindow)


class MyOrganiser(App):
    def build(self):
        return MainWindow()

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

Answer 1

You can use ScreenManager and Screen for this.
An example:

from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder


class MainWindow(Screen):
    pass

class Button1(Screen):
    pass


root = Builder.load_string('''

<MainWindow>:
    name: "mainwindow"
    FloatLayout:
        Button:
            text: "Goto Button1"
            on_release: root.manager.current = "button1"
<Button1>:
    name: "button1"
    FloatLayout:
        Button:
            text: "Goto MainWindow"
            on_release: root.manager.current = "mainwindow"

ScreenManager:
    MainWindow:
    Button1:

''')



class MyApp(App):
    def build(self):
        return root


MyApp().run()

And in a Python only version, as requested by the OP:

from kivy.app import App
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import Button


class MainWindow(Screen):

    def __init__(self,**kwargs):
        super(MainWindow,self).__init__(**kwargs)

        self.name = "mainwindow"
        self.fl = FloatLayout()
        self.button = Button(text="Goto Button1")
        self.button.bind(on_release=self.goto)

        self.fl.add_widget(self.button)
        self.add_widget(self.fl)

    def goto(self,*args):
        self.manager.current = "button1"



class Button1(Screen):

    def __init__(self,**kwargs):
        super(Button1,self).__init__(**kwargs)

        self.name = "button1"
        self.fl = FloatLayout()
        self.button = Button(text="Goto MainWindow")
        self.button.bind(on_release=self.goto)

        self.fl.add_widget(self.button)
        self.add_widget(self.fl)

    def goto(self,*args):
        self.manager.current = "mainwindow"



class MyApp(App):
    def build(self):
        sm = ScreenManager()
        sm.add_widget(MainWindow())
        sm.add_widget(Button1())
        return sm

MyApp().run()