freezing canvas ?

["Florent.Devin" <Florent Devin lifl fr>]

Hi,
For some reason (strange?), I found canvas too quick :-)
How can I freeze the canvas ?
I've try : 
gtk_layout_freeze (GTK_LAYOUT (canvas));
doing something like drawing line, and hiding object, ...
gtk_layout_thaw (GTK_LAYOUT (canvas));

but when I run this code, I saw all modification that I am doing. So
how can I freeze the drawing on canvas ?
Is there any reason that can force my canvas to ignore the freeze
order ?
-- Florent