title: Change button or label text color in kivy
body: <p>I'm following <a href="http://my.safaribooksonline.com/book/programming/python/9781783281596" rel="noreferrer">this kivy book</a>, and while I can understand how to change the background color of buttons, I haven't found the keyword to change the text color.</p>
  
  <p>I saw <a href="https://stackoverflow.com/questions/20181250/changing-the-background-color-of-a-button-in-kivy">this</a> and <a href="https://stackoverflow.com/questions/12997545/how-do-i-change-the-color-of-my-widget-in-kivy-at-run-time">other</a> questions.  Here's my code:</p>
  
  <pre><code>#!/usr/bin/kivy
  import kivy
  kivy.require('1.7.2')
  
  from random import random
  from kivy.app import App
  from kivy.uix.widget import Widget
  from kivy.uix.gridlayout import GridLayout
  from kivy.graphics import Color, Ellipse, Rectangle
  
  class MinimalApp(App):
      title = 'My App'
      def build(self):
          root = RootLayout()
          return(root)
  
  class RootLayout(GridLayout):
      pass
  
  if __name__ == '__main__':
      MinimalApp().run()
  </code></pre>
  
  <h1>and in the .kv file:</h1>
  
  <pre><code>#:kivy 1.7.2
  #:import kivy kivy
  
  &lt;RootLayout&gt;:
      rows: 1
      Label:
          text: "Why does this not work?"
  #        rgba: 1,0,1,1                  # doesn't work
  #        Color:                         # doesn't work
  #                rgba: 1,0,1,1          # doesn't work
  #       font_color: rgba: 1,0,1,1
          canvas.before:
              Color:
                  rgba: 0, 0, 0, 1
              Rectangle:
                  pos: self.pos
                  size: self.size
  </code></pre>