[pygtk] How to draw on root window with a tranparent layer

[Sam Lin]

Hi,

I want to develpe an utility similar to compiz annotate plugin
( http://wiki.compiz.org/Plugins/Annotate )

I GUESS I need to create a transparent canvas then use cairo to draw on it.
How can I get this transparent surface ?

I took a look on annotate code and found it uses a call
"cairo_xlib_surface_create_with_xrender_format()".
Any way to create such a surface with pygtk, pycairo and bind it with
root window (or a decorated-less window) ?

Any suggestion ?

Sam Lin