set form_def {
  GuidoForm form {
    -label "GuidoComboBox Form"
    -default_buttons

    GuidoComboBox plot_size {
      -label "Select the plot size"
      -width 10
      -null false
      -exclusive true
      -value_in A0 A1 A2 A3 A4
    }
  }
}

SclCreateGuidoForm form_handle $form_def {}
$form_handle SclRun {}

puts "The plot size is $plot_size"
