title: Can you change the attributes of a Canvas object after creation?
body: <p>I'm trying to simulate an American traffic light, with 3 circles on a rectangle, all drawn on a set Canvas. The simulation is supposed to mirror "animation" by changing which light is displayed every 2 seconds in the following order: green > yellow > red > green, etc forever.</p>
  
  <p>The only way I can think of to do this is by using a canvas.move(), canvas.after(), canvas.update() pattern to move a filled oval object to superimpose one unfilled circle at a time. I've gotten the logic down to move a circle at the proper speed and in the correct order. The thing is, I just instantiate a circle filled with "green", but I can't change it to be "yellow" or "red" using this method. It seems silly to have to canvas.delete("filled") and redraw it in a new place with a different fill every 2 seconds, because that's a lot to do for such a simple program.</p>
  
  <p>Question 1: Is there a way I can just alter the <code>fill</code> option for my filled Canvas object at will, using some method or other means?</p>
  
  <p>Question 2: Am I approaching this scenario incorrectly? Is there a better way to simulate this?</p>