Noob: Radio button to open window with other radio buttons

[Peter <sw98234 hotmail com>]

I am new to gtk+ and have a capability question.

I have a box with four radio buttons.
I would like one of those buttons, when clicked, to open up a child window
with 9 additional radio buttons.
I would like the child window to return its value. If a different radio
button is selected, I want the child window to be removed.

Is this possible?

choice_1 choice_2 choice_3 radio_4

radio 4 would open a new box with 9 options

radio_4 -> choice_5.....choice_13

I would like that value to be returned by the original radio group.

Right now, I have learned to get a value from the original radio group and
handle the callback. I read through the tutorial, but it was not clear on
this particular matter (or I am just dense :)).

Thanks for any tips.
-- 
Peter