title: Kivy: Update TextInput after picking value from Spinner or Dropdown
body: <p>Im trying to create GUI with kivy but can't figure this.Created Popup screen and trying to pick value from dropbox and add this value to my TextInput.</p>
  <p><strong>test.py:</strong></p>
  <pre class="lang-py prettyprint-override"><code>    from kivy.app import App
      from kivy.uix.textinput import TextInput
      from kivy.uix.dropdown import DropDown
      from kivy.uix.spinner import Spinner
      from kivy.uix.screenmanager import ScreenManager,Screen
      from kivy.uix.popup import Popup
      from kivy.properties import ObjectProperty
      
      class MyDropDown(DropDown):
          def on_select(self, data):
              print('Selected value:',data)
              #Lets add this data to TextInput ?
              MyTextInput.text = data
              #Lets check is that actual text ?
              print('MyTextInput.text is:',MyTextInput.text)
              #HOW CAN I ADD THIS TEXT TEXTINPUT AFTER THAT?
      
      class MySpinner(Spinner):
          dropdown_cls = ObjectProperty(MyDropDown)
      
      class MyTextInput(TextInput):
          pass
      
      class MyTestPopup(Popup):
          my_popup_spinner = ObjectProperty()
          my_textinput_id = ObjectProperty()
      
      class TestPage(Screen):
          MypagePopup = ObjectProperty()
          def open_my_popup(self, *args):
              #Lets create my popup
              self.MypagePopup = MyTestPopup()
              self.MypagePopup.my_popup_spinner.values = ['Test1','Test2','Test3','Test4','Test']
              self.MypagePopup.open()
      
      class TestPageManager(ScreenManager):
          pass
      
      class test(App):
          def build(self):
             return TestPageManager()
      
      if __name__=='__main__':
          test().run()
  </code></pre>
  <p><strong>test.kv:</strong></p>
  <pre><code>&lt;TestPageManager&gt;:
      TestPage:
          name: 'mainpagename'
  &lt;MySpinner&gt;:
      text: 'Pick Value'
  &lt;MyDropDown&gt;:
      values: ['Test1','Test2','Test3','Test4','Test5']
  &lt;MyTextInput&gt;:
  &lt;MyTestPopup&gt;:
      my_popup_spinner : my_popup_spinner
      my_textinput_id : my_textinput_id
      BoxLayout:
          orientation: 'vertical'
          Label:
              text: 'Testing Label Area..'
              pos: self.pos
              size: self.size
          MyTextInput:
              id: my_textinput_id
          MySpinner:
              id: my_popup_spinner
          Button:
              text: 'Done'
              on_release:
                  print('MyTextInput id is :',my_textinput_id.text)
  &lt;TestPage&gt;:
      Button:
          text: 'Open Popup'
          on_release: root.open_my_popup()
  </code></pre>
  <p>As you can see I created like that GUI.</p>
  <p>But can't update TextInput after pick from spinner.How can i update this textinput after pick value from dropbox.I can't figure it out.I think i correctly describe my problem. Thanks for reading and answering.</p>