SDL2错误？应用程序未收到外部键盘输入事件。 （iPhone上的Kivy / Python）

Question

我想在我的应用程序中添加外部键盘操作。键盘在Mac / Kivy环境下工作正常，但是在 iPhone （通过 toolchain.py 发送）上，键盘输入事件丢失了 在出现TextInput 对话框之后。 在以下示例中，可以通过“ Enter”键将MyLayout2切换到MyLayout1，但是不能通过“ Enter”将MyLayout1切换到MyLayout2。我认为这可能是由于SDL2版本引起的，所以我将其更新为最新版本2.0.10，但没有任何更改。是SDL2的 bug ？

Python代码

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import NumericProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.textinput import TextInput
from kivy.core.window import Window
sm = ScreenManager()
class MyLayout1(BoxLayout):
    pass
class MyLayout2(BoxLayout):
    pass
class MyScreen(Screen):
    dialog_number = 0
    def __init__(self, **kwargs):
        super(MyScreen, self).__init__(**kwargs)
        self.gridlayout = None
        self.gridlayout = MyLayout2()
        self.add_widget(self.gridlayout)
        Window.bind(on_key_up=self._keyup)
    def _keyup(self,*args):   
        print(args[2])
        if (args[2] == 40):
            if self.dialog_number == 0:
                self.button2_clicked()
            elif self.dialog_number == 1:
                self.button1_clicked()

    def button1_clicked(self, *args):
        if self.gridlayout is not None:
            self.remove_widget(self.gridlayout)
        self.gridlayout = MyLayout2()
        self.add_widget(self.gridlayout)
        self.dialog_number = 0

    def button2_clicked(self, *args):
        if self.gridlayout is not None:
            self.remove_widget(self.gridlayout)
        self.gridlayout = MyLayout1()
        self.add_widget(self.gridlayout)
        self.dialog_number = 1

class myApp(App):
    def build(self):  
        self.myscreen = MyScreen(name = 'myscreen') 
        sm.add_widget(self.myscreen)
        sm.current = 'myscreen'
        return sm

if __name__ == '__main__': 
    myApp().run()

Kivy代码

<MyScreen>:
    BoxLayout:
        orientation: 'vertical'
        padding: 10,40,10,40 
        spacing: 40 

<MyLayout1>:
    Button1:
        id: btn1
        text: '<MyLayout1> OK or ENTER key'
        on_release: root.parent.button1_clicked()  


<MyLayout2>:
    txtinput: txtinput
    orientation: 'vertical'
    TextInput:
        id: txtinput
        text: ''
        multiline: False
        focus: True
    button2:
        id:Button2
        text: '<MyLayout2> OK or ENTER key'
        on_release: root.parent.button2_clicked()  

<Button0@Button>:
<Button1@Button>:
<button2@Button>: