By default, the AllowToggleRadio property is False. The AllowToggleRadio property on True, allows a radio button to set on zero ( unchecked ), if the user clicks twice the radio button. Usually, clicking a radio-button makes the previously checked radio-button in the same group, to be un-checked, and the newly clicked item to be checked. Now, if the AllowToggleRadio property is True, clicking again the radio-button, allows the radio-button to be un-checked, so allows a radio group to have no radio button checked. The control fires the CheckItem event once a radio-button is clicked.  The Radio property specifies whether the item displays a radio-button. The RadioGroup property specifies a group of radio-buttons.  A radio group allows a single radio-item to be checked. The Checked property specifies whether the item is checked or un-checked. The GetRadio method gets a safe array with the radio-items being checked within a radio group. Use the Background(exRadioButtonState0)/Background(exRadioButtonState1) property to specify the visual appearance of the radio-buttons in the control. Use the UseVisualTheme property to specify whether the visual appearance for the radio-buttons to be as indicated by the current XP theme.