Re: [gtk-list] Re: default signals Q

[pavel <pavel klebanov ne mediaone net>]

Thanks,

exactly what I was looking for!

Pavel

On Thu, 13 May 1999, Federico Mena Quintero wrote:

> >  1. For some reason, when I do what you suggest with "delete_event"
> >  the gpointer *is not* passed to the callback. Is this a bug or
> >  the intended behavior?
> 
> The delete_event is an event signal, so make sure your callback has
> the correct prototype:
> 
>   gint my_callback (GtkWidget *widget, GdkEventAny *event, gpointer data);
> 
> >  2. If "delete_event" is a distinct event, how come binding the callback to
> >  the "destroy" event also works for the "delete_event"? (Or is "destroy"
> >  the default for "delete_event" unless you specify a callback for destroy.)
> 
> When a toplevel window gets a delete_event, it means the window
> manager has sent a request to it asking to close itself.  It is up to
> the program to decide what to do.  You could make your delete_event
> handler prompt the user if he wants to close a window for an unsaved
> file, for example.  Returning FALSE specifies that the delete_event
> "was not handled" and so Gtk can take the default action, which is to
> destroy the window.  If you return TRUE instead, it means the event
> "was handled" and Gtk will do nothing else.
> 
> Now, the destroy signal is completely orthogonal.  It is sent to
> objects when they are destroyed.  For a toplevel window widget, if
> nobody handles a delete_event sent to it, the window will be
> destroyed and the destroy signal will of course be emitted for it.
> 
> >  In any case what I'm trying to accomplish is to have a toggle button which
> >  opens and closes a certain window. Of course, if the user tries to close
> >  the window by clicking on the WM's delete button I want the effect to be
> >  the same as if the toggle button was pressed. Since I have to untoggle the
> >  button when that happens, I have to pass something to the "delete_event"
> >  callback.
> 
> So pass a pointer to the button as your closure data.
> 
> 	gtk_signal_connect (GTK_OBJECT (my_window), "delete_event",
> 			    GTK_SIGNAL_FUNC (delete_event_cb),
> 			    my_toggle_button);
> 
> 	static gint
> 	delete_event_cb (GtkWidget *widget, GdkEventAny *event, gpointer data)
> 	{
> 		gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (data), FALSE);
> 		gtk_widget_hide (widget);
> 		return TRUE;
> 	}
> 
> This assumes you will be only hiding/showing the window instead of
> destroying and re-creating it every time.  If you want to do the
> latter, you can do away with simply connecting to the destroy signal
> and un-toggling the button there.
> 
> 	gtk_signal_connect (GTK_OBJECT (my_window), "destroy",
> 			    GTK_SIGNAL_FUNC (destroy_cb),
> 			    my_toggle_button);
> 
> 	static void
> 	destroy_cb (GtkObject *object, gpointer data)
> 	{
> 		gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (data), FALSE);
> 	}
> 
> Good luck,
> 
>   Federico
> 
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