Kivy change keyboard layout for different text inputs

Question

I am having a hard time changing between keyboard layouts in my app. In the below example I have two text fields and I want one to use a regular keyboard and the other to use a numberpad keyboard. When I click within one text field the keyboard changes, but focus is lost.

Is there a better way of changing a keyboard based on what field currently has focus?

from kivy.config import Config
Config.set('kivy', 'keyboard_mode', 'dock')

from kivy.app import App
from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.clock import Clock
from kivy.properties import ObjectProperty

Window.size = (480, 600)
Window.borderless = False

KV = '''
AnchorLayout:
    anchor_x: "center"
    anchor_y: "center"
    
    BoxLayout:
        orientation: "vertical"
        size_hint: 0.9, 0.5

        MDTextField:
            id: textField
            hint_text: "Text field"
            mode: "rectangle"
            on_focus: app.changeKeyboard(textField, 'keyboard_text.json')

        MDTextField:
            id: numberField
            hint_text: "Number field"
            mode: "rectangle"
            on_focus: app.changeKeyboard(textField, 'keyboard_number.json')
'''


class MyApp(MDApp):
    textField = ObjectProperty()
    numberField = ObjectProperty()

    def build(self):
        return Builder.load_string(KV)

    def changeKeyboard(self, widget, layout):
        self._keyboard = Window.request_keyboard(self._keyboard_closed, widget)

        if self._keyboard.widget:
            vkeyboard = self._keyboard.widget
            vkeyboard.layout = layout

    def _keyboard_closed(self):
        print('My keyboard has been closed!')
        self._keyboard = None


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