Paintable Canvas Basics

General Discussion
2

It looks like you have to explicitly tell the canvas to repaint itself.

Create a custom boolean property on your canvas called changeColor:

Add a binding for the custom property to point to a tag that changes:

Change the if statement in your code:

[...snip...]
if event.source.changeColor:
	g.setColor(Color.GREEN)
else:
	g.setColor(Color.DARK_GRAY)
[...snip...]

And add the following to the propertyChange event of the canvas:

if event.propertyName == "changeColor":
	event.source.repaint()