One button of a new radio button field: where its widget goes and the on state that selects it.
public sealed class PdfRadioButton
ISO 32000-2 §12.7.5.2.4: each widget of a radio button field has an appearance for its on state and for Off; the field's
value (V) is the on state of the selected button. Buttons with the same on state turn on together when the field's
RadiosInUnison flag is set.
kind:method, kind:property, kind:ctor. Press Esc to clear.PdfRadioButton(PdfPage, PdfRectangle, String)Initializes a new instance of the PdfRadioButton class.