gspread和kivy throw问题，分开工作

Question

我想从Google电子表格标题中创建一个下拉菜单。虽然分别使用下拉菜单可以从Google电子表格中获取信息，但是当我将两者结合使用时，会出现错误消息。

import gspread
from oauth2client.service_account import ServiceAccountCredentials
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.base import runTouchApp

scope = ['https://spreadsheets.google.com/feeds', 'https://www.googleapis.com/auth/drive']
creds = ServiceAccountCredentials.from_json_keyfile_name('frisbee.json', scope)
client = gspread.authorize(creds)

sh = client.open('Teams')
worksheet_list = sh.worksheets()
wsl = str(worksheet_list).split()

for word in wsl:
    if "Worksheet" in word:
        wsl.remove(word)
for word in wsl:
    if "id" in word:
        wsl.remove(word)
for word in wsl:
    if "<Worksheet" in word:
        wsl.remove(word)

dropdown = DropDown()
for index in range(len(wsl)):
    btn = Button(text=wsl[index], size_hint_y=None, height=44)
    btn.bind(on_release=lambda btn: dropdown.select(btn.text))
    dropdown.add_widget(btn)

mainbutton = Button(text='Teams', size_hint=(None, None))
mainbutton.bind(on_release=dropdown.open)
dropdown.bind(on_select=lambda instance, x: setattr(mainbutton, 'text', x))

runTouchApp(mainbutton)

预期结果：弹出一个带有下拉菜单的窗口。

实际结果：

[INFO   ] [Text        ] Provider: sdl2
[CRITICAL] [App         ] Unable to get a Window, abort.