Draw on DrawingArea

[vincenzo cappello <ilkapo tiscali it>]

Hey,

I'm working on a graphic editor.

I use a DrawingArea widget, and overwrite the on_expose_event for
perform drawing operation on the cairo context. 

I need to perform drawing operation also on user input, so I overwrite
also on_motion_notify_event, on_button_press_event and
on_button_release_event.
My question is where to implements drawing operation for user input. I
need to call queue_draw() method and then handle this on the
on_expose_event, or I can get the "active" cairo context on the mouse
events and so using this?

Any help would be appreciated.