Re: Beginners question abour events

[Douglas Phillipson <dougp intermind net>]

Murray Cumming wrote:
> On Sun, 2004-02-29 at 17:03, Douglas Phillipson wrote:
>
> > I can't seem to find why you return TRUE, or FALSE at the end of an 
> > event routine like:
> >
> > static gboolean
> > button_press_event( GtkWidget *widget, GdkEventButton *event )
> > {
> >   if (event->button == 1 && pixmap != NULL)
> >       draw_brush (widget, event->x, event->y);
> >
> >   return TRUE;
> > }
> >
> > What happens if you return FALSE when you should be returning TRUE?
> > How do you know what you should be returning?
>
>
> Here's the gtkmm version of the explanation:
> http://www.gtkmm.org/gtkmm2/docs/tutorial/html/apbs06.html

I understand what the difference is between returning TRUE and FALSE in 
a handler now (thankyou for the link).  Now how do you tell which you 
should use?  Example code I see like:

-------------------------------------------------------------
static gboolean
expose_event (GtkWidget * widget, GdkEventExpose * event)
{
  gdk_draw_drawable (widget->window,
             widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
             pixmap,
             event->area.x, event->area.y,
             event->area.x, event->area.y,
             event->area.width, event->area.height);

  return FALSE;
}
-------------------------------------------------------------
then there is:
-------------------------------------------------------------
static gboolean
button_press_event (GtkWidget * widget, GdkEventButton * event)
{
  if (event->button == 1 && pixmap != NULL) {
    draw_brush (widget, event->x, event->y);
  }

  return TRUE;
}
-------------------------------------------------------------
Why is the expose event returning FALSE?  If this implies something else 
must be done in the event mechanism, what is remaining?  Where might 
this be documented?

The button press event seems to be done so it returns TRUE.  Is there 
something else I could do, or the gtk/gdk system would/could do with 
button events if I returned FALSE?

Thanks

Doug P