title: Kivy running but no window appear
body: <p>After kivy installation, I ran the code below</p>
  
  <pre><code>import kivy
  from kivy.app import App
  from kivy.uix.Button import Button
  class Welcome(App):
      def build(self):
          return Button(text = "Welcome to kivy")
  if __name__ == '__main__':
      wel = Welcome();
      wel.run();
  </code></pre>
  
  <p>No error came up and I got this in my console:</p>
  
  <blockquote>
    <p>[INFO   ] [Logger      ] Record log in
    C:\Users\Classic.kivy\logs\kivy_17-05-24_0.txt [INFO   ] [Kivy
    ] v1.10.0 [INFO   ] [Python      ] v3.6.0 (v3.6.0:41df79263a11, Dec 23
    2016, 07:18:10) [MSC v.1900 32 bit (Intel)]<br>
    ----------------------------------------------------------------------  Ran 0 tests in 0.000s    OK</p>
    
    <p>[INFO   ] [Logger      ] Record log in
    C:\Users\Classic.kivy\logs\kivy_17-05-24_0.txt [INFO   ] [Kivy<br>
    ] v1.10.0 [INFO   ] [Python      ] v3.6.0 (v3.6.0:41df79263a11, Dec 23
    2016, 07:18:10) [MSC v.1900 32 bit (Intel)]<br>
    ----------------------------------------------------------------------  Ran 0 tests in 0.000s    OK</p>
  </blockquote>
  
  <p>My OS is Window 10.</p>