Move wxListBox-specific part to wxListBox documentation, it doesn't apply to the other controls, such as wxRadioBox. Also improve the documentation of wxRadioBox::GetSelection() to mention that it always returns a valid value. Closes #18968.
Move wxListBox-specific part to wxListBox documentation, it doesn't apply to the other controls, such as wxRadioBox. Also improve the documentation of wxRadioBox::GetSelection() to mention that it always returns a valid value. Closes #18968.