I’m trying to copy the code that is presented on the official website from the developers of MDTopAppBar:

from kivy.lang import Builder
from kivy.metrics import dp
from kivymd.app import MDApp
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.snackbar import MDSnackbar

KV = '''
MDBoxLayout:
    orientation: "vertical"

    MDTopAppBar:
        title: "MDTopAppBar"
        left_action_items: [["menu", lambda x: app.callback(x)]]
        right_action_items: [["dots-vertical", lambda x: app.callback(x)]]

    MDLabel:
        text: "Content"
        halign: "center"
'''


class Test(MDApp):
    def build(self):
        self.theme_cls.primary_palette = "Orange"
        self.theme_cls.theme_style = "Dark"
        menu_items = [
            {
                "text": f"Item {i}",
                "on_release": lambda x=f"Item {i}": self.menu_callback(x),
            } for i in range(5)
        ]
        self.menu = MDDropdownMenu(items=menu_items)
        return Builder.load_string(KV)

    def callback(self, button):
        self.menu.caller = button
        self.menu.open()

    def menu_callback(self, text_item):
        self.menu.dismiss()
        MDSnackbar(text=text_item).open()


Test().run()

I get a completely different result from what is stated on the site. When trying to create something of my own whatever i try MDTopAppBar does not display any content and remains empty. What is wrong?

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