A GtkRadioButton is one of a group of similar
widgets, only one of which may be selected at any one time.
In the version of GTK+ currently used by PHP-GTK there is an issue with
the "activate" signal where it
is used alongside toggle switches in arrays. In this particular widget,
the "clicked" signal is the
activating signal, and as a result of this feature repeats itself when
another group member is activated.
One way around this is to use the
"pressed" signal. Another would
be to set up a count for each individual function and test that the count
is not divisible by 2. Or, depending on the kind of function you are
calling, you could simply allow
"clicked" to be fired twice.