Re: Weird RadioButton behaviour

[Tadej Borovšak <tadeboro gmail com>]

Hi.

> I have an application on which a group of RadioButtons select the
> control mode. The modes that are not "in control" show the current
> reading, while the "in control" has a SpinButton. To do this widget
> switching I have hooked up to the signal_toggled and signal_clicked of
> the RadioButtons and in the handler I check the get_state() value.
>
> This works fine when I click on the radio buttons with the mouse. The
> callback is invoked four times; twice on the old selection with the
> get_state returning false, then twice on the new with get_state() true.
> I don't know which order the clicked and toggled signals occur but it
> doesn't really matter. I am slightly surprised that I get two events on
> the old  button - I haven't clicked it, after all.

I did have similar troubles quite some time ago. IIRC, the problems
were caused by the fact that GtkButton::clicked is an action signal
that gets emitted quite a lot by GTK+ itself.

It's been a while since I last looked at GTK+'s sources, but I think
that chain of events/signals that lead to observed behavior is:

Clicking with a mouse: GtkToggleButton::button-released ->
GtkButton::clicked -> GtkToggleButton::toggled

Not sure what would chain for keyboard navigation be, but I'm almost
sure that state change is done via GtkButton::clicked signal.

> The problem is when I use the cursor keys to change button. Most times
> it works the same, but often (and it seems to usually be most times I
> move away from a particular button) the two signals sent by the
> "leaving" button happen with its get_state() still returning true.
>
> Presumably this is a race condition of some sort, but why is it so
> consistently problematic on keyboard actions and never on mouse? Is
> there a better way to do the whole thing?

Why do you connect to both GtkButton::clicked and
GtkToggleButton::toggled signals? It would probably be better to only
connect to toggled one.

Hope this helps a bit,
Tadej

-- 
Tadej Borovšak
tadeboro.blogspot.com
tadeboro gmail com
tadej borovsak gmail com