I think bwr30060 answered you
Code:
dialog Nick_Dialog {
  title "Nicks/Chans"
  size -1 -1 109 106
  option dbu
  button "Add", 2, 48 21 37 12
  radio "Nicks", 3, 40 49 50 10, group
  radio "Chans", 4, 40 67 50 10
  box "Example Dialog", 1, 2 2 97 95
}
alias test dialog -m nick_dialog nick_Dialog

On *:Dialog:Nick_Dialog:sclick:2: {
  if ($did(Nick_Dialog,3).state == 1) {
    echo -a Nicks selected
  }
  elseif ($did(Nick_Dialog,4).state == 1) {
    echo -a Chans selected
  }
}