title: Python Kivy Canvas wont Update
body: <p>I am creating a 'Map editor' using 64x64 tiles. I need my canvas to update when i click and change the tile at location. I originally set the canvas with</p>
  
  <pre><code>with self.canvas:
      Rectangle(source = 'image.png')
  </code></pre>
  
  <p>in one class, then in my touch_down class i call</p>
  
  <pre><code>with self.canvas:
      Rectangle(source = 'newImage.png')
  </code></pre>
  
  <p>after i change my image to update it.</p>
  
  <p>I have been able to get it to update but i have to create a new image each time, it seems it wont update since i already added that rectangle with that specific source image, and doesn't see that the image has been changed?</p>
  
  <p><strong>In response to Ryan P</strong></p>
  
  <p>Still nothing. I tried this</p>
  
  <pre><code>Class mypaintwidget(Widget): #This is added as a widget to my layout
      def on_touch_down(self, touch):
          with self.canvas:
              self.rect = Rectangle(source = 'image.png')
          tilepng = pil.open('64x64tile.png') #pil is Python Image Library
          tilemap = pil.open('image.png')       
          tilemap.paste(tilepng,location)
          tilemap.save('newimage.png')
          self.rect.source = 'newimage.png'
  </code></pre>
  
  <p>It will only update ONCE. then nothing (but will still save that image, but wont show it to me.</p>