title: Python : How add a datepicker in .kv file
body: <p>Can anyone tell me how to add a <code>date picker</code> or kivy calendar on <code>date</code> TextBox?<br/>
  I have two file <code>test.py</code> and <code>test.kv</code> file.<br/></p>
  
  <h1>test.py</h1>
  
  <pre><code>import kivy
  import sqlite3 as lite
  
  from kivy.uix.screenmanager import Screen
  from kivy.app import App
  from kivy.lang import Builder
  from kivy.core.window import Window
  from kivy.uix.label import Label
  
  
  Window.clearcolor = (0.5, 0.5, 0.5, 1)
  Window.size = (400, 125)
  
  
  class Testing(Screen):
      pass
  
  class Testing(App):
  
      def build(self):
          self.root = Builder.load_file('test.kv')
          return self.root
  
  
  if __name__ == '__main__':
      Testing().run()
  </code></pre>
  
  <h1>test.kv</h1>
  
  <pre><code>Testing:
      BoxLayout:
          orientation: "vertical"
          padding : 20, 20
  
          BoxLayout:
              orientation: "horizontal"
              padding: 10, 10
              spacing: 10, 10
              size_hint_x: .55
  
              Label:
                  text: "Date"
                  text_size: self.size
                  valign: 'middle'
                  size_hint_x: .2
  
              TextInput:
                  size_hint_x: .3
  
          BoxLayout:
              orientation: "horizontal"
              padding : 10, 0
              spacing: 10, 10
              size_hint: .5, .7
              pos_hint: {'x': .25, 'y':.25}
  
              Button:
                  text: 'Ok'
                  on_release:
                      root.dismiss()
  
              Button:
                  text: 'Cancel'
                  on_release: root.dismiss()
  </code></pre>