Cairo and Gstreamer Cairooverlay

I wanna overlay some lines during a video playing. I'm using Python.
Using a "signal", I set the context :

self.cr = widget.window.cairo_create()

and then "automatically", the drawing function is called:

def draw_overlay (self,cairooverlay,cr,timestamp,duration):
        self.cr.set_source_rgb(0,0,0)
        self.cr.set_line_width(10)
        self.cr.move_to(10,15)
        self.cr.line_to(20,20)
        self.cr.stroke()

I got no errors, but no lines are drawn.
Suggestions?
Thanks in advance,

FB

--
cairo mailing list
[email protected]
http://lists.cairographics.org/mailman/listinfo/cairo