Drawing with cairo

["Diego A. Fons" <diegofons apexar com>]

Hi,

I'm implementing my own widget to render some plots. In all the 
tutorials and help I've seen the cairo context, needed to draw, is 
_created_ in the on_expose_event() handler, so every time i have to 
redraw the plot I have to draw it completely!
My question is if there is a way of preserve the cairo context intact 
between the the calls to on_expose_event()? Why getting the cairo 
context in the on_realize() handler and storing it in a variable doesn't 
work?

Regards,
Diego A. Fons.