在kivymd中更改屏幕时更改工具栏标题

from kivymd.app import MDApp
from kivymd.uix.screen import MDScreen
from kivymd.uix.toolbar import MDToolbar

class CustomScreen(MDScreen):
    pass

class CustomScreen(MDScreen):
    def set_toolbar_title(self, title):
        toolbar = self.parent.ids.toolbar
        toolbar.title = title

class MyApp(MDApp):
    def change_screen(self, screen_name, title):
        screen_manager = self.root.ids.screen_manager
        screen_manager.current = screen_name
        screen = screen_manager.current_screen
        screen.set_toolbar_title(title)

ScreenManager:
    id: screen_manager
    CustomScreen:
        name: "screen1"
        MDToolbar:
            id: toolbar
            title: "默认标题"

Button:
    text: "切换屏幕"
    on_release: app.change_screen("screen1", "新标题")