Drawing on Clutter Contents

[Alessandro Re <ale ale-re net>]

Hello,
I was trying to draw with Cairo on a Content, but nothing shows up. I saw some examples (included the one in the reference), but I can not see (what I think are) notable differences.

Here's my code, can you please tell me what I am missing?

Thanks!

#!/usr/bin/env python3

import sys
from gi.repository import Clutter as clu
import cairo

def quit(*args):
    clu.main_quit()

def draw_something(canvas, ctx, w, h):
    ctx.set_source_rgb(0xff, 0x00, 0xff)
    ctx.set_line_width(3)
    ctx.move_to(0, 0)
    ctx.line_to(w, h)
    ctx.stroke()
    return True

#def invalidate(canvas):
#    canvas.invalidate()
#    return True

if __name__ == '__main__':
    clu.init(sys.argv)

    black = clu.Color.new(0x00, 0x00, 0x00, 0xff)

    stage = clu.Stage()
    stage.set_color(black)
    stage.set_size(200, 200)
    stage.connect('destroy', quit)
    stage.show()

    canvas = clu.Canvas()
    canvas.set_size(200, 200)
    canvas.connect('draw', draw_something)
   
    stage.set_content(canvas)
   
#    clu.threads_add_timeout(0, 1000, invalidate, canvas)

    canvas.invalidate()
    clu.main()

~Alessandro