"draw" event fired forever

[onetmt <onetmt gmail com>]

I'm currently in the process of porting to gtk+-3 an old finite
difference calculation application; this application had a custom graph
drawing routine based on gdk_ subsystem that cannot be compiled anymore
against new gtk3 api :( . I succesfully converted every gdk_ invocation
in their cairo_ counterparts, but now I have to substitute the no longer
available "expose-event" with the new "draw" event. The problem is that
it runs continuosly in an infinite loop.

What is the expected mechanism of this new event? How can I refresh the
graph in a clean way as in old expose-event?

TIA

-- 
Hofstadter's Law:
"It always takes longer than you expect, even when you take into account
Hofstadter's Law."