Re: Stopping signals from being passed to parent (possible bug)

[Owen Taylor <owt1 cornell edu>]

"Damon Chaplin" <DAChaplin@email.msn.com> writes:

> Hi,
> 
> Am I right in assuming that if you return TRUE from a signal handler
> then the signal will NOT be passed on to the widget's parent?
> 
> That doesn't always seem to be the case.
> 
> Below is a simple program with a hscrollbar in a window, both set
> up to pass 'button_press' events to the 'on_button_press' handler,
> which always returns TRUE.
> 
> If you click on the scrollbar, both the scrollbar and the window
> get the event.
> 
> (I've also had problems with entry & text - there may be others)
> 
> Damon

The explaination for your observation is that all event signals
are of type GTK_RUN_LAST, which means that the default handler
runs _after_ your handler, so it's its return value that counts,
not yours.

Since the default handlers all return FALSE (Why? I don't know),
the events get propagated to the parents.

To get the behavior you expect, connect the the event with

 gtk_signal_connect_after()

This will make sure your handler gets called after the default
handler, even for GTK_RUN_LAST.

(You could also make an explicit check:

   if (event->window == widget->window)
      ...

 in your event handler for the parent to filter out such propagated
 events)

Regards,
                                        Owen