Re: connect_notify weirdness, once again...

[Matthias Kaeppler <nospam digitalraid com>]

Murray Cumming wrote:
> On Tue, 2005-04-05 at 21:50 +0000, Matthias Kaeppler wrote:
>
> > Hello,
> >
> > I'm once again having trouble using connect notify. I'm still uncertain why I
> > need this function at all, the documentation is lacking at this point.
> >
> > What I want to do is showing a context menu when the client right-clicks my
> > treeview. Okay, here come the questions:
> >
> > 1. The documentation says I either have to inherit from TreeView and overwrite
> > on_button_press_event() or use connect_notify to bind an own function from which
> > I call the base class handler. What's the reasoning here? Why can't I just
> > directly override on_button_press_event()?
>
>
> You can, as you said above.
>
> But you often can not connect a signal with connect() instead of
> connect_notify(), because the existing signal handler specifies (via the
> return value) that other signal handlers (yours) should not be called.
> This is not a great API, but luckily
> 1) It's only for X-Event signal handlers, and they are relatively rare.
> 2) It's documented.
>
> There's a bug open about this. I haven't given up hope of making this
> simpler in future:
> http://bugzilla.gnome.org/show_bug.cgi?id=126213
> (The TreeView is mentioned in a dependent bug.)

Is this also the case for the signal_button_press_event?
Because I am connecting (not connect_notify'ing) a signal handler which 
returns a boolean to that signal, and it is never called.
OTOH, this signal handler (handling mouse button presses) doesn't sound 
to be "rare":

class MyWidget: public Gtk::ScrolledWindow
{
public:
    bool on_button_press_event( GdkEventButton* );
// ...
private:
    Gtk::TreeView view_;
// ...
}

// ...
view_.signal_button_press_event().connect( sigc::mem_fun( *this, 
&MyWidget::on_button_press_event ) );

The signal handler is never called. I have to declare it void and 
connect with connect_notify().
I still don't get the point.

PS: Can you also reply to my other post regarding signal handlers in 
general, i.e. when signal_button_press_event is fired if I have an 
overlapping view and a widget, which both can fire this event.


Thanks in advance.
--
Matthias Kaeppler