Edit: (since you posted some code), just use:
active = [r for r in self.updatePageRadio.get_group() if r.get_active()]
and use that to look up in a dict of functions and call it:
Edit: I totally forgot to mention that this is not a good use-case at all for RadioButtons, regular gtk.Button would be much better in my opinion.
Your answer is to use the RadioButton "groups" system. It is explained in this document, but here is a small practical example.
Firstly a group is really just a RadioButton itself that is used to collect a number of other RadioButtons. You specify a group as the first argument to the constructor.
r1 = gtk.RadioButton(None, label='Cat') # this has no group, it is the first
r2 = gtk.RadioButton(r1, label='Mouse') # use the first radio
# button as the group argument
r3 = gtk.RadioButton(r1, label='Dog') # again use r1
Now all the radio buttons will be synchronised. And the matter of reading them is as easy as:
active_radios = [r for r in r1.get_group() if r.get_active()]
The documentation you linked to shows this:
seekbar.connect("value-changed", control_changed, label)
seekbar.connect("notify::fraction", fraction_changed, label)
So it seems it has (at least) two signals called "value-changed" and "notify::fraction". It also shows an inheritance diagram that tells you that the Seekbar inherits the standard GTK+ Scale widget, which is where the first signal comes from (by further inheritance).
Not sure where the "notify::fraction" signal comes from, though.
I agree with Michael, but for the record this can be done.
One way to do this would be to have a hidden radio button that you could activate, which would then cause all the visible ones to be inactive. Quick n' Dirty example: