another simple ( I imagine ) problem

[Andy Gilman <amgilman myfairpoint net>]

I am trying to write an extremely simple program, which will be animated 
by showing an image, then redrawing it one pixel over, etc.

I have followed the clock example in the tutorial with the following 
successes:

the image is displayed.
the timer works
the timer connects to a function (following the clock example),

But I can't figure out how to redraw the image.

Here is the function that I thought would lead to the image disappearing 
(Header is the drawing area):

bool Header::update()
{
Glib::RefPtr<Gdk::Window> win = get_window();
    if (win)
    {
      Gdk::Rectangle r(600, 2, 70,70);// this is the rectangle where 
the image is displayed
      win->invalidate_rect(r, false);
    };
return TRUE;
}

Thanks for any help.

Andy Gilman