尝试在MDToolbar中存在单击图标时显示MDDropDownMenu

from kivymd.app import MDApp
from kivymd.uix.toolbar import MDToolbar
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.button import MDIconButton

class MyApp(MDApp):
    def build(self):
        toolbar = MDToolbar(title="My App", pos_hint={'top': 1})
        self.icon = 'icon.png'
        self.theme_cls.primary_palette = "Blue"
        self.theme_cls.theme_style = "Light"
        self.toolbar = toolbar
        return toolbar

def show_menu(self, button):
    menu_items = [
        {
            "viewclass": "MDMenuItem",
            "text": "Item 1",
            "callback": self.menu_item_callback
        },
        {
            "viewclass": "MDMenuItem",
            "text": "Item 2",
            "callback": self.menu_item_callback
        },
        {
            "viewclass": "MDMenuItem",
            "text": "Item 3",
            "callback": self.menu_item_callback
        }
    ]
    self.menu = MDDropdownMenu(
        caller=button,
        items=menu_items,
        width_mult=4,
    )
    self.menu.open()

def menu_item_callback(self, text):
    print(text)

def build(self):
    ...
    icon_button = MDIconButton(icon="dots-vertical")
    icon_button.bind(on_release=self.show_menu)
    toolbar.add_widget(icon_button)
    ...

if __name__ == "__main__":
    MyApp().run()